The Case and Power Supply - Choosing a Power Supply
(Page 8 of 9 )
Now that you understand the role and components of a power supply, itís time for you to decide on a power supply of your own. Of course, you need to consider a few factors when youíre preparing to choose one. Remember that youíll want one that will last a long time, at least through several upgrades, and possibly for the entire life of your computer.
When choosing a power supply, treat your decision as seriously as you would when choosing any other aspect of your system. In the beginning of this chapter, you read that the power supply is one of the most overlooked and disregarded components of a PCóhopefully, you now know enough about this vital component to dispel that myth.
Hereís what to consider when you choose a power supply.
Power supplies are rated in wattage (W), which can be determined by multiplying voltage and amperage. This is a tedious way to figure load, but you can, if you wish, determine the current needs of every device and peripheral you plan to assemble in your PC and choose a power supply based on your calculations. For example, a motherboard might use 5A (amps) of power on a 5V line, requiring 25W. A floppy driveís logic uses .5A at 5V, for 2.5W. Two PCI slots filled use 4A, and this is all powered by the 5V current, so thereís another 20 watts. Meanwhile, the 12V current powers the 3Ĺ-inch drive motor with 1A, the floppy motor also uses 1A, and CD and DVD-ROM drives use 1A eachóchalk up 48 more watts.
You can crunch the numbers by using V◊Aand come up with a wattage requirement if you wish, and you can obtain the voltage and amperage requirements of every peripheral you plan to install. If you do this, buy a power supply with a greater capacity than you need to cover for any upgrades that you may add in the future. For example, if you end up calculating that you need 268W, get a 300W or 350W power supply.
There is a simpler way. Consider that youíre going to be using your computer for a long time. You might add new drives at any time, you may upgrade the processor and/or motherboard, and you might add a hard drive. Since youíre not building a disposable system, but one that you can upgrade as needed, your system is unlikely to be static for a long period of time. Therefore, youíll want to choose a power supply with more wattage than you currently need. For a high-end gamerís system like youíre going to build, you shouldnít go with less than a 350W or 400W power supply.
Not all power supplies are equal in terms of how well they protect your system from brownouts, blackouts, and surges. High-end power supplies contain safety circuitry that will protect the other components in your system, even at the expense of the power supply itself.
Look for power supplies with PC protecting features that can deal with problematic AC. This is especially important if you donít use an external power protection device, such as a surge protector, a power conditioner, or a UPS, which are all discussed in their own sections a little later in the chapter.
Throughout this book, the noise factor of your PC is discussed. Itís no fun to play games and work next to a computer that sounds like a Leer jet taking off for Maui. Power supplies are one of the noisiest components in the PC with their dual fans running all the time. Only recently have power supply manufacturers begun to address this issue, adding tricks like heat-sensitive fans that adjust their RPM speed according to the cooling needs, or just plain quiet-running fans.
You donít want a generic power supply. As with most components, itís always better to spend a little more money on a name-brand item. Youíll get a better warranty, accessible tech support, and generally better quality than you will with a generic model. Some brands to look at for power supplies are Antec, PC Power and Cooling, and Enlight. My personal favorite power supply, which fulfills all of these conditions, is Antecís TruePower line, available in a number of watt ratings. I tend to go with the True430 for my high-end systems.
AC power is noisy, and itís prone to brownouts, surges, and other destructive factors that can damage a power supply or even internal computer components. No matter how wonderful your power supply is, itís a good idea to have some sort of external power protection to keep destructive AC influences from reaching your PC altogether.
External power protection comes in a bunch of different forms and at all kinds of price points. Surge protectors are usually inexpensive, line conditioners are priced in the middle, and uninterruptible power supplies (UPSs) are relatively expensive. Each offers a different level of protection.
This chapter is from Build Your Own High Performance Gamers' Mod PC, by Chen and Durham (McGraw-Hill/Osborne, 2004, ISBN: 0072229012). Check it out at your favorite bookstore today. Buy this book now.
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