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Upgrading & Repairing PCs Eighth Edition

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# Building a System

- System Components
  - Case and Power Supply
  - Motherboard
  - I/O Ports
  - Floppy Disk Drive
  - Hard Disk Drive
  - CD-ROM Drive
  - Keyboard and Pointing Device (Mouse)
  - Video Card and Display
  - Sound Card and Speakers
  - Accessories
- System Assembly
- Sources and Suppliers

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In these days of commodity parts and component pricing, building your own system from scratch is no longer the daunting process it once was. Every component necessary to build a PC-compatible system is available off the shelf, and at very competitive pricing. In many cases, the system you build can use the same components as the top name-brand systems.

There are, however, some cautions. The main thing to note is that you rarely save money when building your own system compared to purchasing a complete system from a mail order vendor or mass merchandiser. The reasoning for this is simple: Most system vendors today who build systems to order use many if not all the same components you can when building your own. The difference is that they buy these components in quantity and receive a much larger discount than you can purchasing only one of a particular item.

There also is only one shipping or handling charge when you purchase a complete system instead of the individual shipping charges when you purchase separate components. In fact, the shipping, handling, and even phone charges from ordering all of the separate parts needed to build a PC often add up to $100 or more. This cost rises if you encounter problems with any of the components and have to make additional calls or send improper or malfunctioning parts back for replacement.

It is clear that the reasons for building a system from scratch often has less to do with saving money than with the experience and end result. In the end, you have a custom system that contains the exact components and features you have selected. The experience itself is also very rewarding. You know exactly how your system is constructed and configured because you have done it yourself. This makes future support and installation of additional accessories much easier.

It may be possible to save some money using components of your current system when building your new system. You might have recently upgraded your hard drive or memory in an attempt to extend the life of your current computer. You can take those components with you to the new system in most cases, if you plan appropriately. For example, if you used 30-pin SIMMs in your old system, you can buy a new motherboard that supports both 72- and 30-pin SIMMs, or buy a SIMM adapter to convert your 30-pin SIMMs to 72.

So if you are interested in a rewarding experience, want to have a custom system that is not exactly offered by any vendor, want to save some money by re-using some of the components from your current system, and you are not in a hurry, then building your own PC-compatible may be the way to go. On the other hand, if you are interested in getting a PC-compatible for the best price, want one-stop support for warranty claims, and need an operational system quickly, then building your own system should definitely be avoided!

This chapter details the components needed to assemble your own system, explains the assembly procedures, and lists some recommendations for components and their sources.

## System Components

The components used in building a typical PC compatible are:

- Case and power supply
- Motherboard:

  Processor | Parallel
  Memory | IDE
  Serial | Floppy

- Floppy disk drive
- Hard disk drive(s)
- CD-ROM drive
- Keyboard and pointing device (mouse)
- PCI video card and display
- Sound card and speakers
- Accessories:

  Heat sinks/cooling fans | Hardware
  Cables | Operating system software

- Heat sinks/cooling fansHardwareCablesOperating system softwareEach of these components is discussed in the following sections.

### Case and Power Supply

The case and power supply is usually sold as a unit. There are several designs to choose from, most of which will take a standard Baby-AT or the new ATX form factor mother-boards. The size of the case, power supply, and even the motherboard are called the form factor. The most popular case form factors are as follows:

- Full Tower
- Desktop
- Mid-Tower
- Low Profile (also called Slimline)
- Mini-Tower

Out of these choices, it is recommended that you avoid the Low Profile systems. These cases require a special type of motherboard called a Low Profile or LPX board. LPX motherboards have virtually everything built in, even video, and do not have any normal adapter slots. Instead, all of the expansion slots are mounted on a "tree" board called a riser card, which plugs into a special slot on the motherboard. Adapter cards then plug sideways into the riser card, making expansion somewhat limited and difficult.

Most of the case designs other than the Low Profile (or Slimline) take a standard sized motherboard called a Baby-AT type. This designation refers to the form factor or shape of the motherboard, which is to say that it mimics the original IBM AT but is slightly smaller. Actually, the Baby-AT form factor is a kind of a cross between the IBM XT and AT motherboard sizes.

Many of the newer cases accept the standard Baby-AT form factor motherboards as well as the ATX-style boards, but an older case designed for Baby-AT motherboards does not accept an ATX motherboard. The ATX form factor will eventually replace the Baby-AT style for most newer motherboards. So if you are interested in the most flexible type of case and power supply that will support future upgrades, look for a unit that conforms to the ATX and Baby-AT motherboard form factors.

Whether you choose a desktop or one of the tower cases is really a personal preference. Most feel that the tower systems are easier to work on, and the full-sized tower cases have lots of bays for different storage devices. Tower cases have enough bays to hold floppy drives, multiple hard disks, CD-ROM drives, tape drives, and anything else you might want to install. Some of the desktop cases also can have as much room as the towers, particularly the mini- or mid-tower models. In fact, a tower case can really be considered a desktop case turned sideways or vice versa. Some cases are convertible-- that is, they can be used in either a desktop or tower orientation.

### Motherboard

There are several compatible form factors used for motherboards. The form factor refers to the physical dimensions and size of the board, and dictates what type of case the board will fit into. The types of motherboard form factors generally available are the following:

- Full-size AT
- ATX
- Baby-AT
- LPX

The full-size AT motherboard is so named because it matches the original IBM AT motherboard design. This allows for a very large board of up to 12 inches wide by 13.8 inches deep. The keyboard connector and slot connectors must conform to specific placement requirements to fit the holes in the case. This type of board will fit into the tower or full-sized desktop cases only. Because the cases that will fit these boards are more limited in availability, and due to component miniaturization, the full-size AT boards are no longer being produced by most motherboard manufacturers.

The Baby-AT form factor is essentially the same as the original IBM XT motherboard, with modifications in screw hole positions to fit into an AT-style case (see Figure 19.1). These motherboards also have specific placement of the keyboard connector and slot connectors to match the holes in the case.

> NOTE: Virtually all full size AT and Baby-AT motherboards use the standard 5-pin DIN type connector for the keyboard. Baby-AT motherboards will fit into every type of case except the Low Profile or Slimline cases. Because of their flexibility, this is now the most popular motherboard form factor. Figure 19.1 shows the dimensions and layout of a Baby-AT motherboard.

The newest form factor on the market today is the ATX form factor, which was released by Intel in July 1995 (see Figure 19.2). This motherboard design is featured on many new Pentium and Pentium Pro-based motherboards and should continue to be featured over the next few years, and it is destined to replace the Baby-AT form factor. ATX-shaped boards are the same basic dimensions as Baby-AT; however, they are rotated 90 degrees from the standard Baby-AT orientation. This places the slots parallel to the short side of the board, allowing more space for other components without interfering with expansion boards. Components that produce large amounts of heat, such as the CPU and memory, are located next to the power supply, which is redesigned to feature an internal fan blowing directly across the board.

The ATX-style power supply also features a redesigned single keyed (foolproof!) connector that cannot be plugged in backwards, and it also supplies the motherboard with 3.3v for many of the newer CPUs and other components.

Consider that if you don't purchase an ATX form factor motherboard this time, the next time you probably will! Virtually all motherboard manufacturers have committed to the new ATX design in the long run, as the ATX motherboard designs will be cheaper, easier to access for user serviceability, and more reliable.

Other form factors used in motherboards today are the LPX and Mini-LPX form factors. These form factors require the use of a Low Profile case and are normally not recommended when building your own system. This is due to the number of different variations on case and riser card designs. These types of form factors are popular with many of the PC systems sold through retail outlets and appliance stores.

FIG. 19.1 Baby-AT motherboard form factor.

> TIP: There can be some differences between systems with LPX motherboards, so it is possible to find interchangability problems between different motherboards and cases. I usually do not recommend LPX style systems if future upgradability is a factor; it is not only difficult to locate a new motherboard that will fit, but LPX systems are also limited in expansion slots and drive bays as well. Generally, the Baby-AT configuration is the most popular and the most flexible type of system to consider.

Besides the form factor, there are several other features you should consider in a motherboard. The primary considerations would be the processor type and chipset. Motherboards you should consider would have a socket for one of three different processor families:

- Pentium
- Pentium with MMX (MultiMedia eXtension)
- Pentium Pro
- Pentium II

FIG. 19.2 ATX motherboard form factor.

Pentium motherboards will normally have a Zero Insertion Force (ZIF) Socket 7 (321-pin), which is available in speeds from 120MHz to 233MHz. MMX is an extension of the Pentium line that includes additional instructions to handle and accelerate multimedia function calls, such as video and sound. The Pentium II is to the Pentium Pro as the Pentium with MMX is to the Pentium. The Pentium II processor is Intel's newest processor family and is becoming a popular alternative among the highest end systems that run full 32-bit OSes, for example, Windows NT.

Depending on the exact processor version you install and the speed at which it is to be run, there may be jumpers on the motherboard to set. There may also be jumpers to control the voltage supplied to the processor; these should be carefully checked or the board and processor will not operate properly.

There are a few other items to consider when purchasing a motherboard. Besides the processor, the main component on the board would be the chipset. This is normally a set of one to five chips that contain the main motherboard circuits. These chipsets replace the 100 or more discrete components that were used in the original IBM AT systems, and allow a motherboard designer to easily create a functional system. The chipset will contain the local bus controller (usually PCI), the cache controller, main memory controller, DMA and Interrupt controllers, and several other circuits as well. The chipset used in a given motherboard will have a profound effect on the performance of the board, and will dictate performance parameters and limitations such as cache size and speed, main memory size and speed, processor types and speeds, and more.

Because chipsets are constantly being introduced and improved over time, I cannot possibly list all of them and their functions, but as an example, I will discuss some of the popular ones for Pentium-based systems. There are several very popular high performance chipsets designed for Pentium motherboards on the market today. The best of these offer support for EDO (Extended Data Out) RAM, pipeline burst cache SRAM (Static RAM), PCI local bus, and Advanced Power Management (APM), as well as other functions, such as IDE interfaces.

Here are several of the high-performance chipsets available for Pentium-based motherboards:

- Intel Triton/Triton II. The 82430FX PCIset (called Triton) and HX (called Triton II) are both four chipsets. The Triton chipset consists of the 82437FX Triton System Controller (TSC), two 82438FX Triton Data Paths (TDP), and the 82371FB PCI ISA IDE Xcelerator (PIIX). The TSC integrates the cache and main memory control functions and provides bus control for transfers between the CPU, cache, main memory, and the PCI Bus. The L2 cache controller in the TSC supports write-back cache for cache sizes of 256 and 512K, as well as lower cost cacheless designs. Cache memory can be implemented with either standard, burst, or pipeline burst SRAMs. The TSC and TDPs together support up to 128M of EDO or standard main memory. The PIIX acts as a PCI to ISA bridge, and includes the DMA controllers, interrupt controllers, timer/counter, power management support, and an Enhanced IDE interface with up to two IDE connectors for four IDE devices.

> NOTE: The original (FX suffix) version Triton chipset unfortunately does not support parity-checked RAM. This means that any motherboard built with this chipset will not be able to detect memory errors during system operation. Even if you purchase parity SIMMs, the parity will not be used. Many system integrators will not use non-parity RAM in mission-critical systems, such as file servers. Because of market pressures demanding such support, Intel has released a second-generation (HX suffix) Triton II chipset that includes both parity and ECC (Error Correcting Code) memory support.

- Opti Viper. The 82C550 Viper-DP from Opti supports not only the Pentium, but the AMD K5 and Cyrix M1 processors as well, in both single and dual processor configurations. The Viper-DP chipset consists of three chips: the 82C556 Data Buffer Controller (DBC), the 82C557 System Controller (SC), and the 82C558 Integrated Peripherals Controller (IPC). The SC is the main chip and contains the main memory controller, L2 cache controller, and the PCI and VL-Bus interfaces. The IPC contains the ISA bus controller, DMA and Interrupt controllers, and PCI to ISA bridge. The DBC buffers the CPU and main memory and contains the parity generation and checking circuits. Viper supports up to 512M of EDO or standard main memory with or without parity checking, and up to 2M of L2 write-back cache using either asynchronous, burst, or pipeline burst SRAMs.
- ALI Aladdin. The Aladdin M1510 chipset from Acer Laboratories Inc. also supports the Pentium, AMD K5, and Cyrix M1 series processors in both single and dual processor configurations. Aladdin M1510 is a four-chip set. It includes the M1511 Memory/Cache Controller that supports EDO RAM as well as standard RAM up to 768M with or without parity checking.
- This chip also supports up to 1M of L2 write-back cache, including support for standard burst and pipeline burst SRAMs. The M1513 System I/O Controller contains the PCI bus interface, DMA and Interrupt controllers, timer circuits, and PCI Enhanced IDE interface, as well as an integrated keyboard controller. Finally, two M1512 data buffers are used to serve as an intermediate between the CPU and main memory.

The choices for Pentium II motherboard chipsets are a little more restricted. As of this printing, only a couple of chipsets are available, including the Intel Orion and Natoma chipsets. Intel's original Pentium Pro (Pentium II without MMX support) chipset was code-named Orion and is technically known as the 82450GX or KX. This chipset is generally made up of seven individual chips and supports up to four Pentium Pro processors and two separate PCI buses in the GX server version. A desktop version of Orion, the 82450KX, supports two processors and a single PCI bus.

More recently, Intel released a less expensive and more efficient Natoma chipset for Pentium Pro machines. Natoma is technically called the 82440FX chipset and consists of only three chips rather than seven as with Orion. Natoma supports only two Pentium Pro processors and a single PCI bus, making it less suited to servers than the GX version of the Orion chipset. However, the greater internal efficiency of Natoma makes it a better performer overall than Orion.

No matter what Pentium class chipset you look for, I would recommend looking for the following supported features:

- EDO RAM (main memory)
- Pipeline Burst (also called Synchronous) SRAM cache
- Parity generation and checking
- ECC memory support
- APM (Advanced Power Management) energy saving functions
- MMX support (if you plan to do any multimedia)
- PCI Local Bus

Most of the better Pentium chipsets on the market today should have these features. If you are buying a motherboard, I highly recommend you contact the chipset manufacturer and obtain the documentation (usually called the Data Book) for your particular chipset. This will explain how the memory and cache controllers, as well as many other devices in your system, operate. This documentation will also describe the Advanced Chipset Setup functions in your system's Setup program. With this information, you may be able to fine-tune the motherboard configuration by altering the chipset features. Because chipsets are discontinued and new ones are introduced all the time, don't wait too long to get the chipset documentation, as most manufacturers only make it available for chips currently in production.

> NOTE: One interesting tidbit about the chipset is that in the volume that the motherboard manufacturers purchase them, the chipsets usually cost about $40 each. If you have an older motherboard and need repair, you normally cannot purchase the chipset because they are normally not stocked by the manufacturer after they are discontinued. The low-cost chipset is one of the reasons mother-boards have become disposable items and are rarely, if ever, repaired.

Another feature on your motherboard will be the BIOS (Basic Input/Output System). This is also called the ROM BIOS because the code is stored in a Read Only Memory (ROM) chip. There are several things to look for here. One is that the BIOS be supplied by one of the major BIOS manufacturers such as AMI (American Megatrends International), Phoenix, Award, or Microid Research. Also, make sure that the BIOS is contained in a special type of reprogrammable chip called a Flash ROM or EEPROM (Electrically Erasable Programmable Read Only Memory). This will allow you to download BIOS updates from the manufacturer and, using a program they supply, easily update the code in your BIOS. If you do not have the Flash ROM or EEPROM type, you will have to physically replace the chip if an update is required.

Make sure that the motherboard and BIOS support the new Plug and Play (PnP) specification. This will make installing new cards, especially PnP cards, much easier. PnP automates the installation and uses special software that is both built in to the BIOS as well as the operating system (such as Windows 95) to automatically configure adapter cards and resolve adapter resource conflicts.

Processor

In most cases, your motherboard comes with the processor already installed. Most of the name-brand motherboard manufacturers like to install the processor and warranty the board and processor as a unit. This is not always the case, and it is definitely possible to purchase the motherboard and processor separately.

The processor normally is installed in a special ZIF socket on the motherboard. Make sure the jumpers on the board are set to match the correct processor type, speed, and voltage.

Memory

Your system will require memory for the Level 2 (secondary) cache as well as the main memory. The cache memory will be in the form of individual SRAM chips, or possibly in what is called COAST (Cache On A Stick) or CELP (Card Edge Low Profile). COAST and CELP are different names for the same thing. This is a new standard for cache SIMMs. COAST/CELP SIMMs have a different number of pins and pinout from standard main memory SIMMs, and are not interchangeable with them.

Most Pentium motherboards support at least 256-512K of cache memory. The chips themselves are available in three basic cache types: standard asynchronous, burst, and pipeline burst. The latter offers the highest performance; choose it if your motherboard supports it. Most of the newer Pentium boards support the pipeline burst cache chips; most of the 486 boards didn't. This is because these faster cache chips are not really needed at the slower 33 to 40MHz memory bus speeds on the 486 compared to the 60 and 66MHz memory bus speeds in a Pentium system.

Main memory will normally be installed in the form of SIMMs (Single Inline Memory Modules) or in some cases the newer DIMMs (Dual Inline Memory Modules). There are three different physical types of main memory modules used in PC systems today, with several variations of each. The three main types are as follows:

- 30-pin SIMMs
- 72-pin SIMMs
- 168-pin DIMMs

The 72-pin SIMMs are by far the most common type of memory module used today; however, just a few years ago most systems came with 30-pin modules. Many of the high-end systems use the DIMMs, because they are 64-bits wide and can be used as a single bank on a Pentium or Pentium Pro system. Depending on the type of processor, a different number of SIMMs must be installed to make a complete memory bank, and the 72-pin SIMMs are four times as dense as the 30-pin types.

For example, in a 486-based system, you would need four 30-pin SIMMs to make a single bank of memory, while only one 72-pin SIMM would be required for a single bank. This is because the 72-pin SIMMs hold data 32 bits wide, while the 30-pin SIMMs only hold data 8 bits wide. A 64-bit Pentium system, then, would require two 72-pin SIMMs or a single 168-pin DIMM to make a single bank.

Memory modules can include an extra bit for each eight to be used for parity checking. These are called parity SIMMs or parity DIMMs and are required by most older boards. Many newer motherboards do not employ parity checking, which means that you will not be able to use the slightly more expensive parity SIMMs. You can install them, but the extra parity bits will not function. I do not necessarily agree with this philosophy, but nevertheless, many newer motherboards (such as those based on the Intel Triton chipset) simply cannot use parity checking at all! Most other chipsets, including the newer Triton II, do support memory parity checking.

Another thing to watch out for is the type of metal on the memory module contacts. They are available with either tin- or gold-plated contacts. While it may seem that gold-plated contacts are better (they are), you should not use them in all systems. You should instead always match the type of plating on the module contacts to what is also used on the socket contacts. In other words, if the motherboard SIMM or DIMM sockets have tin-plated contacts, then you must use SIMMs or DIMMs with tin-plated contacts also.

If you mix dissimilar metals (tin with gold), there will be a rapidly accelerated corrosion occurring on the tin side, and also tiny electrical currents will be generated. The combination of the corrosion and tiny currents causes havoc, and all types of memory problems and errors occur. In some systems, I have observed that everything will seem fine for about a year, during which the corrosion develops. After that, random memory errors result. Removing and cleaning the memory module and socket contacts postpones the problem for another year, upon which the problems return again. How would you like this problem if you had 100 or more systems to support? Of course you can avoid these problems if you insist on using SIMMs with contacts whose metal matches the metal found in the sockets in which they will be installed.

Finally, some systems now use a special type of memory called EDO (Extended Data Out). These memory chips are slightly redesigned and do not cost much more than standard non-EDO memory, but they can operate at increased efficiency in a motherboard designed for them. The actual speed increase varies but is usually not more than a couple of percentage points. Motherboards that use EDO memory also can use standard non-EDO memory, but they will not enjoy the increased performance. You also can install EDO memory in older systems that do not support it because EDO is backward-compatible with standard (called fast page mode) memory. Of course, installing the more expensive EDO modules in an older system will not improve performance.

### I/O Ports

Most motherboards today have built-in I/O ports. If these ports are not built-in, then they will have to be supplied via a plug-in expansion board that unfortunately wastes a slot. The following ports should be included in any new system you assemble:

- Mouse port (so-called PS/2 type)
- Two local bus Enhanced IDE ports (primary and secondary)
- Floppy controller (2.88M capable)
- Two serial ports (16550A buffered type)
- Parallel port (EPP/ECP type)

The standard procedure is to include these ports directly on the motherboard. This is possible because there are several chip companies that have implemented all of these features except the mouse port (which uses the keyboard controller) on a single Super I/O chip! These chips often cost less than $5 in quantities of 1,000 or more, so adding these items directly to the motherboard saves a more expensive board taking up an expansion slot.

If these devices are not present on the motherboard, then various Super or Multi-I/O boards are available that implement all of these ports. Again, most of the newer versions of these boards use a single chip implementation because it is cheaper and more reliable.

### Floppy Disk Drive

Obviously, your system needs some type of floppy drive to load software. Usually, this is a 1.44M 3 1/2-inch drive, but I normally recommend a 2.88M drive these days. The 2.88M drives are superior to the 1.44M drives, and they are fully backward-compatible. Most current controllers and ROM BIOS fully support the 2.88M drives.

If you are interested in a 5 1/4-inch drive, most of the floppy drive manufacturers make combo drives that include both a 3 1/2-inch 1.44M and 5 1/4-inch 1.2M drive in a single unit, which installs in a half-height 5 1/4-inch bay. At least one company (Teac) offers a combo drive that combines a 1.44M floppy and a quad-speed CD-ROM drive in a single unit as well. One drawback of these combo units is that if one of the components fails, the entire combo drive has to be replaced. Also, no one seems to make these with the more desirable 2.88M floppy drives.

### Hard Disk Drive

Your system also needs a hard disk. In most cases, a drive with a minimum capacity of 1.6G is recommended, although in some cases you can get away with less for a low-end configuration; you will be hard pressed to find one smaller. High-end systems should have drives of 2-4G or higher. The most popular interface is IDE, although SCSI is preferred for multitasking OSes. IDE generally offers greater performance for single installations, but SCSI is better for two or more drives or with multitasking operating systems like Windows 95 and NT. This is due to the greater intelligence in the SCSI interface, which relieves some of the I/O processing from the CPU in the system.

There are several brands of drives to choose from, but most of them offer similar performance within their price and capacity categories.

### CD-ROM Drive

A CD-ROM drive should be considered a mandatory item in any PC you construct these days. This is because most software--particularly multimedia programs--is now being distributed on CD-ROM. Systems can now boot from CD-ROM drives (Windows NT 4.0, for example). There are several types of CD-ROM drives to consider these days, but mostly I recommend a minimum of a quad-speed drive interfaced via an IDE connection. This results in the best possible performance with the minimum amount of hassle. If you already have a SCSI adapter, go with a SCSI CD-ROM as well; you'll improve your multitasking performance and save money on an unneeded IDE controller.

### Keyboard and Pointing Device (Mouse)

Obviously, your system needs a keyboard and some type of pointing device, such as a mouse. Different people prefer different types of keyboards, and the "feel" of one type can vary considerably from other types. I suggest that you try a variety of keyboards until you find what suits you best. I prefer a stiff action with tactile feedback myself, but others prefer a lighter, quieter touch.

Because there are two types of keyboard connectors found in systems today, make sure that the keyboard you purchase matches the connector on your motherboard. Most Baby-AT boards use the larger 5-pin DIN connector, and most ATX boards use the 6-pin, mini-DIN connector; however, the trend now seems to be changing to the mini-DIN connector for all boards. On some motherboards, you have an option of choosing either connector when you purchase the board. If you end up with a keyboard and mother-board that do not match, there are several companies that sell adapters to mate either type of keyboard to either type of motherboard connector.

The same concept applies to mice or other pointing devices; there are a number of different choices that suit different individuals. Try several before deciding on the type you want. If your motherboard includes a built-in mouse port, make sure that you get a mouse that is designed for that interface. This mouse is often called a PS/2 type mouse because the IBM PS/2 systems introduced this type of mouse port. Many systems use a serial mouse connected to a serial port, but having a motherboard-integrated mouse port would be better because you would have both serial ports free for other devices.

> TIP: You might be tempted to skimp here to save a few dollars. Don't. You do all of your interacting with your new PC through these devices, and cheap ones make their presence known every time you use your system.

### Video Card and Display

You need a PCI video adapter as well as a monitor or display to complete your system. There are numerous choices in this area, but the biggest piece of advice I have is to choose a good monitor. The display is your main view to the system and can be the cause of many hours of either pain or pleasure, depending on what monitor you choose.

I usually recommend a minimum of a 17-inch display these days. Anything smaller cannot acceptably display 1,024x768 pixel resolution. If you opt for a 15-inch or smaller display, you might find that the maximum tolerable resolution would be 800x600. This may be confusing, because most 15-inch monitors claim to be able to display 1,024x768 resolution or even higher, but the characters and features are so small on-screen at that resolution that excessive eyestrain and headaches will result. If you spend a lot of time in front of your system and want to display the higher resolution, a 17-inch display should be considered mandatory.

Your video card and monitor should be compatible in terms of refresh rate, and a minimum refresh rate for a solid, nonflickering display is 70-72Hz; the higher the better. If your new video card can display 16 million colors at a resolution of 1,024x768 and a refresh rate of 76Hz, your monitor's maximum refresh rate at 1,024x768 is 56Hz, and you can't use the video card to its maximum potential.

### Sound Card and Speakers

You need a sound card and a set of external speakers for any system that is to be multimedia capable. The sound card should be compatible with the Creative Labs Sound Blaster cards, which have set the standards in this area. Getting a sound card with an upgradable memory (the same SIMMs you use for your main memory) enables you to download additional sound samples--speaker size and quality are up to you.

### Accessories

Often you need various accessories to complete your system. These are the small parts that can make or break the assembly process.

Heat Sinks/Cooling Fans

Most of today's faster processors produce a lot of heat, and this heat has to be dissipated or your system will operate intermittently or even fail completely. Heat sinks are available in two main types: passive and active.

Passive heat sinks are simply finned chunks of metal (usually aluminum) that are clipped or glued to the top of the processor. They act as a radiator, and in effect give the processor more surface area to dissipate the heat. I normally recommend this passive design type of heat sink because there are no mechanical parts to fail. In some cases, you should use a thermal transfer grease or sticky tape to fill any air gaps between the heat sink and the processor. This allows for maximum heat transfer and the best efficiency.

An active heat sink includes a fan. These can offer greater cooling capacity than the passive types, but require power and are not known for reliability. They often use a cheap fan mechanism that fails after a year or so, thus allowing the processor to overheat and the system to fail. If you do use an active heat sink with a fan, stay away from cheaper units that may be more failure prone.

> NOTE: Notice that the newer ATX form factor motherboards are designed to eliminate the troublesome and unreliable active heat sink (CPU fan). These systems feature a power supply with reverse flow cooling that blows air directly over the CPU, which is relocated in these systems to take advantage of this. Due to a superior design, the ATX motherboard form factor eliminates the need for any sort of cooling fan mounted directly to the CPU.

Cables

Any PC system needs a number of different cables to hook everything up. These can include power cables or adapters, disk drive cables, CD-ROM cables, and many others. Most of the time, the devices you purchase come with included cables, but in some cases they aren't supplied. The vendor list in Appendix A of this book has several cable and small parts suppliers listed that can get you the cables or other parts you need to complete your system.

Another advantage of the ATX motherboard form factor is that these boards feature externally accessible I/O connectors directly mounted to the rear of the board. This eliminates the "rat's nest" of cables found in the common Baby-AT form factor systems. This feature also makes the ATX system a little cheaper and more reliable as well.

Hardware

You need screws, standoffs, and other miscellaneous hardware to assemble your system. Most of this comes with the case, but in some situations you may need more. Again, you can consult the vendor list in Appendix A for suppliers of small parts and hardware needed to get your system operational.

Operating System Software. You need OS software such as DOS, Linux, or Windows to run your PC. Most software houses carry a selection of appropriate operating system software and any applications you need.

## System Assembly

Actually assembling the system is easy after you have lined up all of the components! In fact, you may find the procurement phase the most lengthy and trying of the entire experience. Completing the system is simply a matter of screwing everything together, plugging in all of the cable and connectors, and configuring everything to operate properly together.

More explicit instructions for installing any of the system components can be found in the section of this book that covers that particular component. For example, to find out about configuring and installing the floppy drive, consult Chapter 13, "Floppy Disk Drives."

In short order, you will find out whether your system operates as you had planned, or whether there are some incompatibilities between some of the components. Be careful and pay attention to how you install all of your components. It is rare that a newly assembled system operates perfectly the first time, even for those who are somewhat experienced. It is easy to forget a jumper, switch, cable connection, and so on, which would cause problems in system operation. The first reaction if there are problems is to blame the problem on defective hardware, but that is usually not the case. Usually the problem can be traced to some missed step or error made in the assembly process.

## Sources and Suppliers

One of the most valuable (to me anyway) parts of this book is the vendor list in Appendix A. Here you will find a number of vendors of different PC components, including addresses, phone numbers, and other information as it is available. These vendors are in this list usually because I recommend their products, or because they are an important company whose products are very popular. There are companies in the vendor list covering all of the components needed to build your system. In some cases, the manufacturers of the components listed will not sell direct to end users, and you may find yourself purchasing through a distributor instead. That is okay; I normally include the actual manufacturers in my list because they can best recommend a distributor for their own products, and of course they should support their own products as well.

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