Many people don’t realize that just like your automobile, computers have unique power requirements. Several years ago I had to help a relative with her car – a 1975 Ford Mustang. She recently had a new stereo system, sub woofer, the whole kit n’ caboodle installed in her Mustang. She complained that her car constantly died and was a bit of an ordeal to start in the mornings. The battery seemed fine, the alternator checked out, but after her new stereo system was installed, she constantly had problems with her car dying. What the problem boiled down to was this: after she upgraded the stereo system in her car, the car’s power requirements went up two fold. The car’s old, factory stock battery could not keep up. With my help she changed out her old car battery for a new, bigger and better battery and the problem was resolved.

Computers are very similar. If you upgrade components in your computer, you also should consider what sort of strain this will place on your computer’s power supply.

Your standard, “bare bones” computer does not require much power. With only one 400 gigabyte hard drive, a dual core processor, 2 gigabytes of RAM, one optical drive… At a minimum you need a 300 watt power supply. With a mid level computer, that is a computer consisting of one, one terabyte hard drive, a Quad core processor, 2 gigabytes of RAM, a high end video card – you definitely need a 500 Watt (or greater) power supply. Anything above that and a 600 – 700 Watt power supply is a must.

For example:

Central Processing Units
Under an extreme level of process tasking, from your computer’s CPU – for example Intel’s Q8400 – you should expect to see around 200 Watts of power consumption.

Hard drives
For hard drives, most manufacturers post their power supply requirement / information online. As a general rule of thumb, though, each hard drive uses about 10 Watts.

Video cards
For Most of the newer video cards – for example the GeForce 9500 GT – the manufacturer’s minimum power requirement is a 500 Watt power supply (or greater). The power consumption, of course, varies per application. Under a heavy processing load, though, you should expect to see about 212 Watts of power consumption.

CD / DVD drives
At the CD / DVD drive’s maximum burst output, you should expect to see about a 25 Watt power consumption.

RAM
Under a heavy load, you should expect to see a 1.5-2 Watt power consumption. This value is based upon Kingston KVR667D2N5 – 1 Gigabyte – DDR2 RAM.

Furthermore, all USB devices (unless powered through an AC/DC adapter) also draw power through the Universal Serial Bus. If you are trying to make a precise estimate of how much your minimum power requirements are, you might also want to take this into consideration.

If you add these values together :
(200 Watts (CPU) + 10 Watts (HDD) + 212 Watts (Video card) + 25 Watts (CD / DVD Drive) + 2 Watts (RAM)) = 450 Watts.

These values were calculated in reference to a basic “mid-level” computer system, as mentioned above.

Just remember: If you upgrade the components of your computer, but neglect to also upgrade your computer’s power supply – the more inevitable it is that you will have problems somewhere down the line.

If you have any questions or comments, be sure to let us know! Thanks for reading.