Computer Virus [ Malware, Trojan, etc ]

Malware, short for malicious software, is software designed to infiltrate or damage a computer system without the owner's informed consent. The expression is a general term used by computer professionals to mean a variety of forms of hostile, intrusive, or annoying software or program code.^[1] The term "computer virus" is sometimes used as a catch-all phrase to include all types of malware, including true viruses.

Software is considered malware based on the perceived intent of the creator rather than any particular features. Malware includes computer viruses, worms, trojan horses, most rootkits, spyware, dishonest adware, crimeware and other malicious and unwanted software. In law, malware is sometimes known as a computer contaminant, for instance in the legal codes of several U. S. states, including California and West Virginia.^[2][3]

Malware is not the same as defective software, that is, software which has a legitimate purpose but contains harmful bugs.

Preliminary results from Symantec published in 2008 suggested that "the release rate of malicious code and other unwanted programs may be exceeding that of legitimate software applications."^[4] According to F-Secure, "As much malware [was] produced in 2007 as in the previous 20 years altogether."^[5] Malware's most common pathway from criminals to users is through the Internet: primarily by e-mail and the World Wide Web.^[6]

The prevalence of malware as a vehicle for organized Internet crime, along with the general inability of traditional anti-malware protection platforms to protect against the continuous stream of unique and newly produced professional malware, has seen the adoption of a new mindset for businesses operating on the Internet - the acknowledgment that some sizable percentage of Internet customers will always be infected for some reason or other, and that they need to continue doing business with infected customers. The result is a greater emphasis on back-office systems designed to spot fraudulent activities associated with advanced malware operating on customers computers.^[7]

Purposes

Many early infectious programs, including the first Internet Worm and a number of MS-DOS viruses, were written as experiments or pranks generally intended to be harmless or merely annoying rather than to cause serious damage to computers. In some cases the perpetrator did not realize how much harm their creations could do. Young programmers learning about viruses and the techniques wrote them for the sole purpose that they could or to see how far it could spread. As late as 1999, widespread viruses such as the Melissa virus appear to have been written chiefly as pranks.

Hostile intent related to vandalism can be found in programs designed to cause harm or data loss. Many DOS viruses, and the Windows ExploreZip worm, were designed to destroy files on a hard disk, or to corrupt the file system by writing invalid data. Network-borne worms such as the 2001 Code Red worm or the Ramen worm fall into the same category. Designed to vandalize web pages, these worms may seem like the online equivalent to graffiti tagging, with the author's alias or affinity group appearing everywhere the worm goes.

However, since the rise of widespread broadband Internet access, malicious software has come to be designed for a profit motive, either more or less legal (forced advertising) or criminal. For instance, since 2003, the majority of widespread viruses and worms have been designed to take control of users' computers for black-market exploitation.^{[citation needed]} Infected "zombie computers" are used to send email spam, to host contraband data such as child pornography^[8], or to engage in distributed denial-of-service attacks as a form of extortion.

Another strictly for-profit category of malware has emerged in spyware -- programs designed to monitor users' web browsing, display unsolicited advertisements, or redirect affiliate marketing revenues to the spyware creator. Spyware programs do not spread like viruses; they are generally installed by exploiting security holes or are packaged with user-installed software, such as peer-to-peer applications.

Infectious malware: viruses and worms

The best-known types of malware, viruses and worms, are known for the manner in which they spread, rather than any other particular behavior. The term computer virus is used for a program which has infected some executable software and which causes that software, when run, to spread the virus to other executable software. Viruses may also contain a payload which performs other actions, often malicious. A worm, on the other hand, is a program which actively transmits itself over a network to infect other computers. It too may carry a payload.

These definitions lead to the observation that a virus requires user intervention to spread, whereas a worm spreads automatically. Using this distinction, infections transmitted by email or Microsoft Word documents, which rely on the recipient opening a file or email to infect the system, would be classified as viruses rather than worms.

Some writers in the trade and popular press appear to misunderstand this distinction, and use the terms interchangeably.

Capsule history of viruses and worms

Before Internet access became widespread, viruses spread on personal computers by infecting programs or the executable boot sectors of floppy disks. By inserting a copy of itself into the machine code instructions in these executables, a virus causes itself to be run whenever the program is run or the disk is booted. Early computer viruses were written for the Apple II and Macintosh, but they became more widespread with the dominance of the IBM PC and MS-DOS system. Executable-infecting viruses are dependent on users exchanging software or boot floppies, so they spread heavily in computer hobbyist circles.

The first worms, network-borne infectious programs, originated not on personal computers, but on multitasking Unix systems. The first well-known worm was the Internet Worm of 1988, which infected SunOS and VAX BSD systems. Unlike a virus, this worm did not insert itself into other programs. Instead, it exploited security holes in network server programs and started itself running as a separate process. This same behavior is used by today's worms as well.

With the rise of the Microsoft Windows platform in the 1990s, and the flexible macro systems of its applications, it became possible to write infectious code in the macro language of Microsoft Word and similar programs. These macro viruses infect documents and templates rather than applications, but rely on the fact that macros in a Word document are a form of executable code.

Today, worms are most commonly written for the Windows OS, although a small number are also written for Linux and Unix systems. Worms today work in the same basic way as 1988's Internet Worm: they scan the network and leverage vulnerable computers to replicate.

oncealment: Trojan horses, rootkits, and backdoors

Trojan horses

For a malicious program to accomplish its goals, it must be able to do so without being shut down, or deleted by the user or administrator of the computer via which it is running. Concealment can also help get the malware installed in the first place. When a malicious program is disguised as something innocuous or desirable, users may be tempted to install it without knowing what it does. This is the technique of the Trojan horse or trojan.

Broadly speaking, a Trojan horse is any program that invites the user to run it, concealing a harmful or malicious payload. The payload may take effect immediately and can lead to many undesirable effects, such as deleting the user's files or further installing malicious or undesirable software. Trojan horses known as droppers are used to start off a worm outbreak, by injecting the worm into users' local networks.

One of the most common ways that spyware is distributed is as a Trojan horse, bundled with a piece of desirable software that the user downloads from the Internet. When the user installs the software, the spyware is installed alongside. Spyware authors who attempt to act in a legal fashion may include an end-user license agreement which states the behavior of the spyware in loose terms, and which the users are unlikely to read or understand.

Rootkits

Once a malicious program is installed on a system, it is essential that it stay concealed, to avoid detection and disinfection. The same is true when a human attacker breaks into a computer directly. Techniques known as rootkits allow this concealment, by modifying the host operating system so that the malware is hidden from the user. Rootkits can prevent a malicious process from being visible in the system's list of processes, or keep its files from being read. Originally, a rootkit was a set of tools installed by a human attacker on a Unix system where the attacker had gained administrator (root) access. Today, the term is used more generally for concealment routines in a malicious program.

Some malicious programs contain routines to defend against removal: not merely to hide themselves; but to repel attempts to remove them. An early example of this behavior is recorded in the Jargon File tale of a pair of programs infesting a Xerox CP-V timesharing system:

Each ghost-job would detect the fact that the other had been killed, and would start a new copy of the recently slain program within a few milliseconds. The only way to kill both ghosts was to kill them simultaneously (very difficult) or to deliberately crash the system.^[9]

Similar techniques are used by some modern malware, wherein the malware starts a number of processes which monitor and restore one another as needed.

Backdoors

A backdoor is a method of bypassing normal authentication procedures. Once a system has been compromised (by one of the above methods, or in some other way), one or more backdoors may be installed, in order. Backdoors may also be installed prior to malicious software, to allow attackers entry.

The idea has often been suggested that computer manufacturers preinstall backdoors on their systems to provide technical support for customers, but this has never been reliably verified. Crackers typically use backdoors to secure remote access to a computer, while attempting to remain hidden from casual inspection. To install backdoors crackers may use Trojan horses, worms, or other methods.

Malware for profit: spyware, botnets, keystroke loggers, and dialers

During the 1980s and 1990s, it was usually taken for granted that malicious programs were created as a form of vandalism or prank. More recently, the greater share of malware programs have been written with a financial or profit motive in mind. This can be taken as the malware authors' choice to monetize their control over infected systems: to turn that control into a source of revenue.

Spyware programs are commercially produced for the purpose of gathering information about computer users, showing them pop-up ads, or altering web-browser behavior for the financial benefit of the spyware creator. For instance, some spyware programs redirect search engine results to paid advertisements. Others, often called "stealware" by the media, overwrite affiliate marketing codes so that revenue is redirected to the spyware creator rather than the intended recipient.

Spyware programs are sometimes installed as Trojan horses of one sort or another. They differ in that their creators present themselves openly as businesses, for instance by selling advertising space on the pop-ups created by the malware. Most such programs present the user with an end-user license agreement which purportedly protects the creator from prosecution under computer contaminant laws. However, spyware EULAs have not yet been upheld in court.

Another way that financially-motivated malware creators can profit from their infections is to directly use the infected computers to do work for the creator. The infected computers are used as proxies to send out spam messages. The advantage to spammers of using infected computers is they provide anonymity, protecting the spammer from prosecution. Spammers have also used infected PCs to target anti-spam organizations with distributed denial-of-service attacks.

In order to coordinate the activity of many infected computers, attackers have used coordinating systems known as botnets. In a botnet, the malware or malbot logs in to an Internet Relay Chat channel or other chat system. The attacker can then give instructions to all the infected systems simultaneously. Botnets can also be used to push upgraded malware to the infected systems, keeping them resistant to anti-virus software or other security measures.

It is possible for a malware creator to profit by stealing sensitive information from a victim. Some malware programs install a key logger, which intercepts the user's keystrokes when entering a password, credit card number, or other information that may exploited. This is then transmitted to the malware creator automatically, enabling credit card fraud and other theft. Similarly, malware may copy the CD key or password for online games, allowing the creator to steal accounts or virtual items.

Another way of stealing money from the infected PC owner is to take control of a dial-up modem and dial an expensive toll call. Dialer (or porn dialer) software dials up a premium-rate telephone number such as a U.S. "900 number" and leave the line open, charging the toll to the infected user.

Data-stealing malware

Data-stealing malware is a web threat that divests victims of personal and proprietary information with the intent of monetizing stolen data through direct use or underground distribution. Content security threats that fall under this umbrella include keyloggers, screen scrapers, spyware, adware, backdoors, and bots. The term does not refer to activities such as spam, phishing, DNS poisoning, SEO abuse, etc. However, when these threats result in file download or direct installation, as most hybrid attacks do, files that act as agents to proxy information will fall into the data-stealing malware category.

Characteristics of data-stealing malware

Does not leave traces of the event

• The malware is typically stored in a cache which is routinely flushed
• The malware may be installed via a drive-by-download process
• The website hosting the malware as well as the malware is generally temporary or rogue

Frequently changes and extends its functions

• It is difficult for antivirus software to detect final payload attributes due to the combinations of malware components
• The malware uses multiple file encryption levels

Thwarts Intrusion Detection Systems (IDS) after successful installation

• There are no perceivable network anomalies
• The malware hides in web traffic
• The malware is stealthier in terms of traffic and resource use

Thwarts disk encryption

• Data is stolen during decryption and display
• The malware can record keystrokes, passwords, and screenshots

Thwarts Data Loss Prevention (DLP)

• Leakage protection hinges on metadata tagging, not everything is tagged
• Miscreants can use encryption to port data

Examples of data-stealing malware

• Bancos, an info stealer that waits for the user to access banking websites then spoofs pages of the bank website to steal sensitive information
• Gator, spyware that covertly monitors web-surfing habits, uploads data to a server for analysis then serves targeted pop-up ads
• LegMir, spyware that steals personal information such as account names and passwords related to online games
• Qhost, a Trojan that modifies the Hosts file to point to a different DNS server when banking sites are accessed then opens a spoofed login page to steal login credentials for those financial institutions

Data-stealing malware incidents

• Eleven people were implicated in a massive identity theft and computer fraud scheme targeting nine U.S. retailers (BJ’s Wholesale Club, TJX, DSW Shoe, OfficeMax, Barnes & Noble, Boston Market, Sports Authority and Forever 21). Over 40 million credit and debit card numbers were stolen. ^[10]
• A Trojan horse program stole more than 1.6 million records belonging to several hundred thousand people from Monster Worldwide Inc’s job search service. The data was used by cybercriminals to craft phishing emails targeted at Monster.com users to plant additional malware on users’ PCs. ^[11]
• Customers of Hannaford Bros. Co, a supermarket chain based in Maine, were victims of a data security breach involving the potential compromise of 4.2 million debit and credit cards. The company was hit by several class-action law suits. ^[12]
• The Torpig Trojan has compromised and stolen login credentials from approximately 250,000 online bank accounts as well as a similar number of credit and debit cards. Other information such as email, and FTP accounts from numerous websites, have also been compromised and stolen. ^[13]

Vulnerability to malware

In this context, as throughout, it should be borne in mind that the “system” under attack may be of various types, e.g. a single computer and operating system, a network or an application.

Various factors make a system more vulnerable to malware:

• Homogeneity – e.g. when all computers in a network run the same OS, if you can exploit that OS, you can break into any computer running it.
• Defects – malware leveraging defects in the OS design.
• Unconfirmed code – code from a floppy disk, CD-ROM or USB device may be executed without the user’s agreement.
• Over-privileged users – some systems allow all users to modify their internal structures.
• Over-privileged code – most popular systems allow code executed by a user all rights of that user.

An often cited cause of vulnerability of networks is homogeneity or software monoculture. In particular, Microsoft Windows has such a large share of the market that concentrating on it will enable a cracker to subvert a large number of systems. Introducing inhomogeneity purely for the sake of robustness would however bring high costs in terms of training and maintenance.

Most systems contain bugs which may be exploited by malware. A typical example is the buffer overrun, in which an interface designed to store data in a small area of memory allows the caller to supply more data than will fit. This extra data then overwrites the interface's own structure. In this way malware can force the system to execute malicious code, by replacing legitimate code with its own payload.

Originally, PCs had to be booted from floppy disks, and until recently it was common for this to be the default boot device. This meant that a corrupt floppy disk could subvert the computer during booting, and the same applies to CDs. Although that is now less common, it is still possible to forget that one has changed the default, and rare that a BIOS makes one confirm a boot from removable media.

In some systems, non-administrator users are over-privileged by design, in the sense that they are allowed to modify internal structures of the system. In some environments, users are over-privileged because they have been inappropriately granted administrator or equivalent status. This is a primarily a configuration decision, but on Microsoft Windows systems the default configuration is to over-privilege the user. This situation exists due to decisions made by Microsoft to prioritize compatibility with older systems above security configuration in newer systems^{[citation needed]} and because typical applications were developed without the under-privileged users in mind. As privilege escalation exploits have increased this priority is shifting for the release of Microsoft Windows Vista. As a result, many existing applications that require excess privilege (over-privileged code) may have compatibility problems with Vista. However, Vista's User Account Control feature attempts to remedy applications not designed for under-privileged users through virtualization, acting as a crutch to resolve the privileged access problem inherent in legacy applications.

Malware, running as over-privileged code, can use this privilege to subvert the system. Almost all currently popular operating systems, and also many scripting applications allow code too many privileges, usually in the sense that when a user executes code, the system allows that code all rights of that user. This makes users vulnerable to malware in the form of e-mail attachments, which may or may not be disguised.

Given this state of affairs, users are warned only to open attachments they trust, and to be wary of code received from untrusted sources. It is also common for operating systems to be designed so that device drivers need escalated privileges, while they are supplied by more and more hardware manufacturers.

Eliminating over-privileged code

Over-privileged code dates from the time when most programs were either delivered with a computer or written in-house, and repairing it would at a stroke render most anti-virus software almost redundant. It would, however, have appreciable consequences for the user interface and system management.

The system would have to maintain privilege profiles, and know which to apply for each user and program. In the case of newly installed software, an administrator would need to set up default profiles for the new code.

Eliminating vulnerability to rogue device drivers is probably harder than for arbitrary rogue executables. Two techniques, used in VMS, that can help are memory mapping only the registers of the device in question and a system interface associating the driver with interrupts from the device.

Other approaches are:

• Various forms of virtualization, allowing the code unlimited access only to virtual resources
• Various forms of sandbox or jail
• The security functions of Java, in java.security

Such approaches, however, if not fully integrated with the operating system, would reduplicate effort and not be universally applied, both of which would be detrimental to security.

Anti-malware programs

As malware attacks become more frequent, attention has begun to shift from viruses and spyware protection, to malware protection, and programs have been developed to specifically combat them.

Anti-malware programs can combat malware in two ways:

1. They can provide real time protection against the installation of malware software on a computer. This type of spyware protection works the same way as that of anti-virus protection in that the anti-malware software scans all incoming network data for malware software and blocks any threats it comes across.
2. Anti-malware software programs can be used solely for detection and removal of malware software that has already been installed onto a computer. This type of malware protection is normally much easier to use and more popular^{[citation needed]}. This type of anti-malware software scans the contents of the windows registry, operating system files, and installed programs on a computer and will provide a list of any threats found, allowing the user to choose which files to delete or keep, or to compare this list to a list of known malware components, removing files that match.

Real-time protection from malware works identically to real-time anti-virus protection: the software scans disk files at download time, and blocks the activity of components known to represent malware. In some cases, it may also intercept attempts to install start-up items or to modify browser settings. Because many malware components are installed as a result of browser exploits or user error, using security software (some of which are anti-malware, though many are not) to "sandbox" browsers (essentially babysit the user and their browser) can also be effective in helping to restrict any damage done.

BIOS / CMOS Setup

This is the BIOS setup for Award BIOS v6.00PG. If you have a different version of the Award BIOS their would be a lot of similarities. If your BIOS is AMI or Phoenix then the common BIOS features would have some similarities. Whatever BIOS you have, this setup guide should give you an idea about how to setup a BIOS. Please note that setting up BIOS incorrectly could cause system malfunction, therefore it is recommended that you also follow the BIOS guide provided on your motherboard manual. If you decide to make changes to certain options it is safer to make a note of what you have changed. Then restart the system to see how it performs. If the system behaves abnormally or becomes unstable you can revert back to your previous settings.

Softmenu III

Softmenu III is where you can setup up the CPU without setting jumpers on the motherboard. You can setup the CPU simply by selecting the speed i.e. Pentium III 750 from the list. This ensures that the CPU bus, multiplier, voltage etc, is correctly set for that particular CPU. However you can manually setup each feature if required. Once you have finished with the setup press ESC to return the previous menu. See figure 1.

Standard CMOS Features

Here you can setup the basic BIOS features such as date, time, type of floppy etc. Use the arrow keys to move around and press enter to select the required option. You can specify what IDE devices you have such as Hard drive, CD-ROM, ZIP drive etc. The easiest way to setup the IDE devices is by leaving it set to auto. This allows the BIOS to detect the devices automatically so you don't have to do it manually. At the bottom, it also displays the total memory in your system. See figure 2.

Advanced BIOS Features

As you can see from figure 3, there are numerous advance settings which you can select if required. For most cases leaving the default setting should be adequate. As you can see the first boot device is set to floppy. This ensures that the floppy disk is read first when the system boots, and therefore can boot from windows boot disk. The second boot device is the Hard disk and third is set to LS120. If you want to boot from a bootable CD then you can set the third boot device to CD/DVD-ROM. See Figure 3.

Advanced Chipset Features

Here you can setup the contents of the chipset buffers. It is closely related to the hardware and is therefore recommended that you leave the default setting unless you know what you are doing. Having an incorrect setting can make your system unstable. If you know that your SDRAM can handle CAS 2, then making changes can speed up the memory timing. If you have 128MB SDRAM then the maximum amount of memory the AGP card can use is 128MB. See Figure 4

Inegrated Peripherals

This menu allows you to change the various I/O devices such as IDE controllers, serial ports, parallel port, keyboard etc. You can make changes as necessary. See figure 5.

Power Management Setup

The power management allows you to setup various power saving features, when the PC is in standby or suspend mode. See figure 6.

PnP/PCI Configurations

This menu allows you to configure your PCI slots. You can assign IRQ's for various PCI slots. It is recommended that you leave the default settings as it can get a bit complicated messing around with IRQ's. See figure 7.

PC Health Status

This menu displays the current CPU temperature, the fan speeds, voltages etc. You can set the warning temperature which will trigger an alarm if the CPU exceeds the specified temperature. See figure 8.

Load Fail-Safe Defaults

If you made changes to the BIOS and your system becomes unstable as a result, you can change it back to default. However if you made many changes and don't know which one is causing the problem, your best bet is to choose the option "Load Fail Safe Mode Defaults" from the BIOS menu. This uses a minimal performance setting, but the system would run in a stable way. From the dialog box Choose "Y" followed by enter to load Fail-Safe Defaults.

Load Optimized Defaults

Like the Fail-Safe mode above, this option loads the BIOS default settings, but runs the system at optimal performance. From the dialog box Choose "Y" followed by enter to load Optimized Defaults.

Set Password

To password protect your BIOS you can specify a password. Make sure you don't forget the password or you can not access the BIOS. The only way you can access the BIOS is by resetting it using the reset jumper on the motherboard.

Save and Exit Setup

To save any changes you made to the BIOS you must choose this option. From the dialog box choose "Y".

Exit without Saving

If you don't want to save changes made to the BIOS, choose "N" from the dialog box.

Hard Disk Drive Setup - Partition and Format

This procedure explains how to setup a new hard disk. Warning - if you are setting up a hard disk which contains data, the following procedure would completely erase your hard disk and the data would be unrecoverable.

Before a new hard disk can be used it needs to be setup. This involves partitioning and formatting the hard disk. Windows 98 or ME boot disk contains the required software to perform this procedure. FDISK.EXE and FORMAT.COM are the files required in your bootable floppy disk. Start the partition and format procedure by booting your PC using a Windows boot disk. Make sure you set the BIOS so that the boot sequence is set to detect the floppy disk first. If your system has no problems booting you will be presented with a Windows boot disk menu. This gives you the option to start the system with or without CD-ROM support. At this stage you do not need the CD-ROM support, so choose the option to boot without CD-ROM support. You should end up in the MS DOS prompt A: (A drive). From A: command prompt type fdisk. You will be presented with following message:

Choose "Y" to enable large disk support.You will now be presented with the FDISK main menu as shown below.

From the menu, choose option 1 - Create DOS partition or Logical DOS drive. Another menu will present the following options.

Choose option 1 - Create primary DOS Partition. FDISK verifies the integrity of your drive and will ask you if want to use the maximum available size of your hard disk to create the primary partition and set it active. To keep things simple we will create one large partition. Choose "Y" to use maximum available space. When the partition has been created successfully you will be notified by the system. Your drive is now known as C: (C drive). Press "Esc" to return to the menu. Press "Esc" again to exit FDISK. You need to restart your system for the changes to take affect. Leave boot disk in the drive.When the system reboots, choose start without CD-ROM from the boot disk menu. While booting from floppy disk you might get error message like "Invalid media type reading drive C" this is OK for this stage as the hard disk is not formatted.

From A: command prompt type format c:You will get a message saying "WARNING, ALL DATA ON NON-REMOVABLE DISK DRIVE C: WILL BE LOST. Proceed with Format (Y/N)?".

Don't worry about the message as you do not have any data in the new hard disk. Choose "Y". The format will proceed and would show you a progress indicator. The time it takes to format a hard disk depends on the size and speed of the drive. This could be around 5-30 minutes. Once the format is complete you need to reset your system. You are now ready to install an operating system.

Finalizing Stage

Now that you have installed all the necessary hardware there are still few more things you need to do before switching on your PC for the first time. Your ATX case has a power switch which turns the PC on, a reset switch for resetting the system, a power LED which comes on when the PC is switched on and a hard drive LED which flashes when data is being written or read from your hard drive. You also have an internal speaker.

Figure 1 - Power and Reset switch

The switches and LED's need to be connected to its corresponding connectors on the motherboard. Please refer to your motherboard manual to locate where the connectors are. Different motherboards place the connectors in different locations. The connectors for the switches and LED's are normally grouped together. They should look similar to the image below.

Figure 2 - Switch and LED connectors

Every cable is normally labeled, they are normally named as follows, but could be slightly different on your system.

Power switch	Power / PWR-SW
Reset switch	Reset
Power LED	Power LED / PWR-LED
Hard drive LED	HDD-LED / IDE LED
Speaker	SPK / Speaker

The connectors on the motherboard are also labeled but may be too small to see. Instead refer to your motherboard manual which would provide details on which pins you should connect the cables to. The image below shows how the pins may be organised on your motherboard.

Once you have connected all the cables to the correct pins on the motherboard, you are ready to switch the PC on. At this point you can close the cover of your ATX case but don't screw it on just yet as you might have possible problems that needs rectifying. Connect all the cables to back of ATX case. These includes the main power cable that connects to the power supply. PS/2 mouse and keyboard that connects to the PS/2 ports. Monitor cable that connects to the graphics card port, etc. Finally the moment has arrived. Switch on your monitor first. Your ATX power supply might have a main power switch at the back so make sure that is switched on. Now switch the PC on by pressing the power switch on the front of the ATX case. If you have performed all the tasks without any mistakes and providing that none of the main components are faulty, the PC should boot. When the PC boots you should see the name of the BIOS manufacturer, such as AWARD BIOS displayed on your monitor. Your CPU type, speed and the amount of memory should be displayed as shown on image below.

If your motherboard has a plug and play BIOS and is set to automatic device detection by default, then you would see your IDE devices being detected followed by a prompt complaining about missing operating system. If your motherboard does not detect the hardware, then you need to proceed to the BIOS setup screen by pressing DEL or F1 or F2 depending on your motherboard. Congratulations you have completed building your own PC. You now need to proceed to the software section which explains how to setup the BIOS, Hard disk and install an operating system.

If things did not go smoothly and your PC does not switch on then go to the troubleshooting section for possible solutions.

Install Modem

Find a free PCI slot on your motherboard (assuming your modem is a PCI modem). Place your modem card on top of the slot and gently push it down into position.

Once the card has seated correctly into position, screw the card to the case using the screws supplied with the case.

Now you have installed all the prerequisite hardware devices. You can either proceed to the finalising stage, or you may want to install optional devices like a ZIP drive, CD-RW drive or a TV-Card. If you do not want to install these devices you can now proceed to the finalising stage.

Install Sound Card

Most modern sound cards are designed with the PCI interface and connects to the PCI slot of your motherboard. A PCI slot looks like the slots on the following image.

Place your sound card on top of a chosen slot. Gently push down the card so it sits into position. Once the card is seated correctly into position, screw the card on to the case.

Finally insert the audio cable into the CD-IN socket. The other end of the cable should be connected to Audio-out socket on your CD/DVD-ROM drive.

Install Graphics Card

Most modern graphics cards are AGP based and connects to the AGP bus of the motherboard. An AGP bus (slot) looks like the following image. The brown slot is where you connect your AGP graphics card.

Place your AGP card on top of the slot and gently push it down. The card should firmly sit into position.

All you need to do now is to screw the metal plate on the front of the card to the ATX case. Use the screws supplied with case and screw the card to the case.

Install CD / DVD-ROM

If you look at the rear side of your CD / DVD-ROM it should look similar to image shown on figure 1.

On the right hand side you have the power connector. Next to power connector you have the IDE connector. On the left hand side near the IDE connector you have the jumper settings for the DVD-ROM. The jumper is set to Master by default. I am connecting the DVD-ROM on a separate IDE cable therefore I will leave the jumper setting to Master. However if you are sharing an IDE cable with another device like HDD, then you would have to set jumper to Slave, as your HDD would be set to Master. Next to the jumpers you have the CD Audio-Out socket. One side of your audio cable connects to this socket and other side connects to the sound card cd-in socket. This would allow you to listen to Audio CD's on your computer.

Figure 1

Figure 2

Mount your CD/DVD-ROM drive into its mounting slot. Use the supplied screws to screw the drive into position.

Figure 3

Connect the IDE cable to the drives IDE connector. Make sure the pin 1 on the cable is connected to pin 1 on the drives IDE connector. Pin 1 is the red or pink strip on the edge of an IDE cable. Connect the other end of the IDE cable to the IDE socket on your motherboard as shown in figure 4. Again, make sure you conncet the cable to pin 1. The IDE socket could be your primary or secondary socket depending which socket you choose. If your HDD is on the primary IDE socket and your secondary IDE socket is free, then it is better to use your secondary IDE socket for the CD/DVD-ROM.

Figure 4

Finally connect the power cable to power connector and connect the audio cable to the CD Audio-Out socket as shown on figure 3.

Install Floppy Disk Drive

The rear side of a floppy drive looks similar to the following image.

The black connector on the left hand side is the floppy disk connector. It is different from the IDE connector and uses a different cable. The small white connector on the right hand side is the power connector for the floppy drive. Figure 1 and 2 below shows what a floppy drive cable and floppy drive power connector looks like.

Figure 1 - Floppy drive cable.

Figure 2 - Floppy drive power cable

Place the floppy drive into the FDD mounting slot as shown. Screw the drive securely into place.

Insert the floppy drive cable into the floppy drive connector. Make sure the pin 1 on the cable connects to the pin 1 on the floppy drive connector. As you already know by now that pin 1 is the red or pink strip on the edge of the floppy drive cable. Most floppy drive cables are designed so that it will only go in on way, so you can not connect it incorrectly.

Push the floppy drive power cable to the power connector. This will only go in on way.

Finally connect the other end of the floppy drive cable to floppy drive connector on your motherboard. Make sure pin 1 on the cable connects to pin 1 on the connector.

Install SATA Hard Drive

If you look at the rear side of a SATA hard drive it should look similar to the image below.

Figure 1 - SATA Hard drive

The SATA cable connector is on the left hand side which consists of few pins. Next to the SATA connector on the right side is SATA power connector which consist of many pins. You will notice that SATA hard drives do not have any jumper settings for slave or master as each drive will connect to a dedicated SATA port on the motherboard.

Place your hard drive into the HDD mounting slot of your case, make sure the SATA connector is facing outwards. Screw the HDD to the case using screws provided with the HDD or the ATX case.

Now have a look at the SATA data cable as show on the image below. You need to connect one end of the SATA data cable to the SATA connector of the hard drive. Look at the top of the cable to see which way it should go in. It would only fit one way so you can not fit it the wrong way round. Gently push the cable into place.

Figure 2 - SATA Cable

The image below is a SATA power connector. This needs to be connected to the power socket of the SATA hard drive. Gently push it into place. It will only fit one way so there is no danger of fitting it wrong way round.

Figure 3 - SATA Power cable

If you have an old ATX power supply you will not have a SATA power connector as they only have 12V molex connector. In this case, if you do not want to replace your power supply unit then you can get a 'Molex to SATA' power cable converter as shown on figure 4.

Figure 4 - Molex to SATA Power cable converter

Finally you need to fit the other end of the SATA data cable to a SATA socket / port on the motherboard. Again it will only fit one way and gently fit into position. It does not matter which socket you plug it into as it will work on any SATA socket. But it is better to plug it into SATA socket 1 if you only have one hard drive. If you add another SATA device you can connect it to SATA socket 2 and so on.

Figure 5 - SATA Socket (port) on motherboard

Install IDE Hard Drive

If you look at the rear side of an IDE hard drive it should look similar to the image below.

The IDE/ATA connector is on the left hand side which consists of many pins. Next to the IDE connector is the jumper setting for the drive. The jumper should be set to Master, which is the default setting for a new HDD. Any other device sharing the same IDE cable should be set to Slave. Different HDD has different jumper settings, please refer to your HDD manual for more information. On the right hand side, next to the jumpers is the power connector. Every device except FDD uses this type of power connector.

Figure 1 and 2 below shows what an ATA 66 and a power cable looks like. The ATA 66 cable which is also known as UDMA 66 cable is an advance IDE cable, which offers higher performance and data integrity than the standard IDE cable. ATA 66 cable consists of 80 conductor cable where as the standard IDE cable consists of 40 conductor cable. I am using an ATA 66 cable because the above HDD is an ATA 100 drive which requires an ATA 66 cable.

Figure 1 - ATA 66 Cable

Figure 2 - Power cable

Place your hard drive into the HDD mounting slot of your case, make sure the IDE/ATA connector is facing outwards. Screw the HDD to the case using screws provided with the HDD or the ATX case.

Insert the ATA 66 cable into the ATA connector of the HDD. Make sure the pin 1 on the cable is connected to pin 1 on the HDD connector. Pin 1 is the red or pink strip on the edge of an ATA cable. Most new IDE/ATA cables are designed so that it will only go in one way which will correspond to pin 1.

Push the power cable into the power connector as shown. The power cable is designed to go in one way, so you shouldn't have any problems.

Connect the other end of the ATA 66 cable to the primary ATA socket of your motherboard as shown. Make sure the pin 1 on the cable connects to the pin 1 on the ATA socket.

That's it you have successfully installed a HDD.

Install Memory - SDRAM

Installing memory is quite simple. Find the SDRAM banks on your motherboard, they should look similar to the banks below. Notice the memory banks has a white clip on each side. Make sure you release the clips so it bends to each side.

Hold each corner of the SDRAM placing it on top of the bank 1. You will notice that the SDRAM has a cut at the bottom side, it is there to prevent the memoy going in the wrong way round. If you are holding the SDRAM the incorrect way you will not be able insert it. Gently push down the SDRAM and it should clip on to the memory bank. The two white clips will now become straight holding each corner of the memory. If you have more that one SDRAM perform same steps as above but placing the SDRAM in memory bank 2 and so on.

Install a Processor (CPU)

Locate the processor socket on your motherboard. I am installing an Intel PIII 866 processor on a socket 370 as shown on the following image. The installation would be slightly different if you have a different processor i.e. Slot1 PIII CPU, P4 Socket 478, Core 2 Duo Socket 775, AMD Slot A / Socket A, Socket AM2 CPU etc.

Raise the brown lever on the socket and slowly put the processor in place. You have to make sure the pin 1 of your CPU goes into the pin 1 of your CPU socket otherwise the CPU would not get into the socket, so don't try to force it in. It will go in gently if you fit it correctly. Now close the brown lever which will securely hold the CPU in place.

If you bought a retail boxed CPU it would include a heatsink + fan. If you bought an OEM CPU make sure you got a fan that is correct for the speed of your CPU, otherwise your CPU will overheat and behave abnormally or could be damaged. Take off the plastic cover from the bottom of the CPU fan that covers the heat transfer pad. Now place the CPU fan on top the CPU and push down the metal clips on the fan so that it clips onto the CPU socket.

CPU fan has a power connector which needs to be connected to CPU fan power socket on your motherboard as shown on the image above.

Finally, you have to specify what frequency (speed) your CPU is running at. This can be done using jumper settings, or on some modern motherboard it can be done in the BIOS, or your motherboard may have automatic detection for your CPU frequency. Please refer to your motherboard manual for more details. The motherboard I am using (Abit BX133) has a dip-stick jumper setting and it can be setup in the BIOS. I have left the jumper setting to default as I will use the BIOS to specify the CPU frequency. The CPU runs at the bus speed of 133Mhz therefore I will use the settings 133 * 6.5(multiplier) under the BIOS, which will the run the CPU at 866Mhz.

Install Motherboard

The first thing you should do is unpack your ATX case. Take off the cover of your case so that you can access the inside. Place the case on a desk so that you are looking down towards the open case. Your case should come with motherboard mounting screws. If your ATX back plate it not already fitted you can fit it by placing your plate near the ATX back plate cut out and pushing the plate outwards, it should clip on.

Now place your motherboard on top of the mounting screw holes. Make sure your ATX devices on the motherboard such as PS/2 and parallel port are facing towards ATX back plate cut out. Gently push your motherboard towards the cut out, every devices should fit easily into its corresponding cut out, as shown below.

The screw holes on your motherboard should align with the screw holes on your case. Place your screws that came with the case into the appropriate holes and gently screw it on using a screw driver.

The motherboard is now securely mounted to the case. You can now place the ATX power connector to the motherboard. Your ATX case should come with a power supply unit (PSU) and should already be mounted to the case. The ATX power connector is shown on image below.

Place the ATX power connector on top of the power socket on the motherboard. Push down the power connector and it should clip onto the socket. If you try to fit the power connector the wrong way round, it won't fit, it will only fit one way. So, if the power connector does not go in, it should go in the other way round.

PC Hardware

To build your PC from scratch you will need to purchase all the necessary hardware. The first thing you must consider before you start to shop around for your PC hardware is the specification of the hardware. You should think about what you are going to use your PC for, before buying fancy expensive hardware. Otherwise you will end up buying hardware which offers advance features that may not be necessary for your needs and end up wasting your money. For example, you may be using your PC for word-processing, spreadsheet and browsing the web. You would not gain much benefit by purchasing an advance 3D graphics card or having a top of the range processor. A simple graphics card and a mid-range processor will satisfy your needs.

Below is a list of all the hardware required to build your system except the obvious requirement, keyboard and mouse. The purpose of each is hardware is explained along with some guidance to help you choose your hardware. Select the required hardware for more information.

Tower or Desktop case	Motherboard
Processor	Memory
Graphics Card	Sound Card
Modem	Floppy Drive
Hard Drive	CD/DVD Rom
PC Speakers	Monitor

CD/DVD Writer	Blu Ray Writer
TV Card	Satellite Card
Cable TV Card