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What you need to build your PC, part 1: The power supply and the motherboard

If you're putting a PC together on your own, you have to know what to look for in individual pieces of hardware. Paul Suiter begins a three-part series on the components of PCs by taking a close look at the power supply and the motherboard.


When most users look at a PC, they don’t see the multiple pieces that make up the machine. They see only a box that does what they want it to do. And when that box doesn’t do what they want fast enough, they go out and get another box that does. It’s a very simple solution. But is it the only solution? You’re spending your money on a system that’s composed of unknown parts; you have no idea who makes them, how they rate, or what their requirements are. In most cases, the name on the front of the PC case is not that of the manufacturer. So, are you really getting a good deal? If you shop around and do the research, you’re probably getting a decent PC for the price. If you are really particular and are getting a PC built especially for you, you may not be.

If you have ever had the nerve or curiosity to look past that box and into the guts of a PC, you probably saw a tangle of wires and ribbon cables running around in a maze of hard drives and expansion cards. This maze is intimidating to some users. But take a closer look. What’s really in there? Not much, actually. No more than a few modular pieces joined together in order to function as a unit.

In this three-part series of Daily Drill Downs, I’ll examine the major components of a PC and briefly describe how they fit together. I’ll point out some of the attributes to look for when you purchase the various pieces. I’ll also discuss some of the terminology that you may run into when you start your quest for parts, and I’ll show you how those terms pertain to what you may need in a particular part.

Major components
Six major components comprise a PC:
  • Power supply
  • Motherboard
  • Processor
  • Memory
  • Video board
  • Drives (a floppy drive and a hard drive)

This configuration exists before the software is added. A PC can run without the operating system (though it doesn’t do very much except start up), but the operating system can’t do anything without the PC. I’ll begin my discussion with the piece that allows all of the others to function: the power supply.

Do you have the power?
Most of us take the power supply for granted. But that box with the noisy fan is the lifeblood of your system. You press the On button, and the PC comes up. If the power supply isn’t working properly, this mild-mannered box can turn your system into junk in a heartbeat. So, choosing a reliable power supply with a good warranty is important.

The power supply works its magic by converting AC power from your wall outlet to the DC power that runs the system devices—straining the working components of the power supply and creating heat in the process. That’s why there’s a cooling fan inside the power supply.

Volts and watts
Generally, when you order the case in which your system will reside, the power supply is already installed. If not, you must purchase it separately. Power supplies are easy to install because they’re a specific size that will fit into almost any case. They’re also designed to work with both 110-volt and 220-volt power outputs, which cover the two common types of electric power outputs. Whether you’re installing a power supply or you’ve received a case with the power supply already installed, make sure that you set the switch on the back of the power supply to the proper voltage that your outlet supports.

The most common wattage level—and the power supply that’s sent with a case, unless otherwise requested—is the 250-watt. Power supplies come in varying wattage amounts. If you want to have several drives, as in a network server, you’ll need a higher wattage power supply, such as a 350-watt. If you’re building a general use desktop model, with one hard drive and a CD-ROM, then the 250-watt will suffice.

Two types of power supplies
There are two types of power supplies that are available: the PS/2 (AT) type and the ATX/NLX type. The AT is an older type that generally has the on/off switch connected directly to the power supply itself. The AT power supply uses a pair of 6-pin connectors through which the power connection for the motherboard is made. The AT type of power supply is generally used with AT or baby AT motherboards.

The ATX/NLX type power supplies are used with the ATX, Mini ATX, and NLX motherboards. The ATX/NLX supply is designed to work through the motherboard by having the on/off power switch connected directly to the motherboard. The ATX power supply connects to the motherboard through a 20-pin connector. Some motherboards come with both AT and ATX types of connectors; thus, some can accommodate the two types of power supplies. In general, however, a good rule to follow is AT boards = AT power supply; ATX boards = ATX/NLX power supply.

Both power supplies come with connectors for running the internal drives of your PC. Usually, the power supply has two types of connectors for the different drives. The larger 4-pin connector is designed for hard drives and CD/DVD ROM drives. The smaller white connector is used for the floppy disk drives. Try to find a power supply that has enough direct power connectors to provide each drive with its own connection. Using splitters when you power internal drives could cause problems down the road.

A smorgasbord of motherboards
The type of motherboard that you use determines the type of power supply and box that you need. But there are two specific aspects of motherboards that you need to understand before you purchase one: form factors and chipsets.

Form factors
Available types of motherboards are divided into form factors, which represent the dimensions of the board. Different CPUs require different boards. You’ll probably see such designations as Socket 7, Super Socket 7, and Slot 1 when you look at motherboards. These designations refer to the type of coupling that the CPU uses to attach to the motherboard. Just because the CPU that you want uses a Socket 7 motherboard doesn’t mean that all motherboards support the CPU that you’ve chosen. Since CPUs come in different MHz values and Pentium grades, it’s very important that you research the specifications of the board. Some boards may be Socket 7 boards but only support older Pentium 133 CPUs.

Currently, the most popular form factor is the ATX because of its integration of the connection ports (serial, USB, PS/2, and parallel) onto the board itself and its easier and better use of power management. The ATX is smaller in size, which allows for smaller cases in both tower and desktop models. The drawback to the smaller size is that it has fewer expansion slots than the AT format does. Surprisingly, the positioning of the CPU socket is better under the ATX format. The CPU is placed away from the expansion slots so that it won’t interfere with the longer cards that are used in the expansion slots.

The AT format is larger and has the upper hand on expansion slots, but most AT form boards don’t have integrated connection ports. The ports are connected to the AT form board by ribbon cable. This design allows the ports to be placed in various locations, but it also adds to the amount of clutter in the box. The CPU is almost always placed in the direct path of the ISA expansion slots. This location could lead to quite a hassle if you’re using full-sized ISA cards that must come across the CPU socket.

The NLX format reduces much of the strain of adding memory and of installing and setting jumpers by making the primary motherboard section a removable card. By placing the CPU connector, memory, and other vital parts on a section that connects to a larger board with the expansion slots, the board remains accessible for modifications and replacement. This format works well for full tower cases, and it’s often seen in proprietary servers.

Chipsets
Motherboards come with what is called a chipset. This portion of the motherboard controls several of your PC’s normal operations, including floppy drives and interrupts. Some of the names that you may come across when you’re looking for a motherboard are Intel, AMD, Apollo, and Opti. All chipsets have advantages in certain areas, and some hardware is designed around certain chipsets. One easy rule to follow is to try to stick with chipsets from the manufacturer that built your CPU. Rival manufacturers of chipsets aren’t likely to add extras for their competitors’ CPUs. Also keep in mind that, as new technology is introduced, chipsets must be manufactured to support this new technology. Chipsets can’t be updated like a BIOS chip can. Make sure that you choose a chipset that will handle all of the devices that you want to use. You ought to research each device that you choose in order to discover if it requires a certain chipset to reach its advertised potential.

My recommendation for purchasing a system board is to look for the newest and most versatile board that both meets your chipset requirements and supports the processor that you want. Research the board and talk to resellers about it. When you get the best available board, you can reduce the amount that you spend on the processor by choosing one that is a little less powerful. It may save you a few hundred dollars, but you’ll still get almost the same speed. You’ll also be ready to upgrade when the more expensive processors come down in price. (Don’t worry; they will come down in price.) Of course, if you have an unlimited budget, you should buy the very best of everything.

Conclusion
Starting with a good foundation of quality power supplies and motherboards can ease many of the problems that users of no-name systems face. What you put into your system is what you’ll get out of it. Selecting your hardware is just as important as selecting your software. In part 2 of this series, I’ll talk about the processor and how it functions in the PC picture. I’ll also take a look at the first of the peripheral devices that hold the software for which you’re building the PC: the hard drive.

Paul Suiter received his first taste of the deadline rush as a photographer for the Montgomery Advertiser, where he earned four photography awards. After receiving degrees in economics and business management from Auburn University, Paul entered the college book business. After managing two bookstores for three years, Paul became a business analyst for EDS. Four years later, Paul continues with EDS, taking its equipment apart, while working with G3 switches and advanced imaging programs. But he’s finally getting back to one of his favorite pastimes—writing. (Of course, he also enjoys spending time with his wife and son.)

The authors and editors have taken care in preparation of the content contained herein, but make no expressed or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for any damages. Always have a verified backup before making any changes.

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