AMD Athlon Buyer's Guide - Part 4: Power Supplies

The Test

We set up two test systems, one indicative of an average Athlon system running an Athlon 750, and the other representing the worst case scenario designed to separate the best power supplies from the rest.  The test system was setup with components recommended by AMD and was configured inside a mid-tower ATX case in order to simulate real world usage.

In order to stress test the power supplies, we created two tests, one to draw as much power as possible from the AGP slot and the next to simulate real world usage at maximum load.

The first test attempts to crash the system by drawing a considerable amount of power from the AGP slot. This is accomplished by running a 3 hour continuous loop of custom multiplayer Quake III Arena demos. The number of crashes that occurred during this 3 hour period were recorded.

The second test attempts to crash the system by drawing power from all areas of the system, thus simulating real world usage. This is accomplished by running 110 consecutive application test runs of the applications included in BAPCo's SYSMark 2000 suite. The number of crashes that occurred during the testing were recorded as a percentage out of the 110 total runs.

The test configurations were as follows:

As you can see, the main differences between the two test systems are the CPU, heatsink/fan, hard drive, and video card. The Athlon 800 requires 8 more Watts than the Athlon 750, so the difference introduced by the higher clock speed Athlon should make a small but noticeable difference in the power draw of the system.

The MC1000 cooler helps stress the +12V power rail as it draws a total of 6.66 amps (A) at 12V. This coupled with the 10,000 RPM Cheetah 2 that is also running off the +12V power rail and you have a combination that can be very stressful on a power supply, especially if it can't deliver enough current on that +12V rail.

The video card used in the second system is a DDR Quadro whereas the first system used a "slower" DDR GeForce. The main difference between these two is that the Quadro runs at a higher clock speed of 135MHz and thus draws more power from the AGP slot. This, along with the higher clock speed Athlon, helps stress the +3.3V and +5V power rails.