I first installed the Zalman ZM500-HP into my main box, completely forgetting (brain fart!) that 500 W not sufficient to power an 8800 GTX. I did take some pictures, though, because installation pictures are always nice. nVidia's control panel did warn me that the 8800 GTX wasn't getting sufficient power, though, and underclocked the GPU in order to keep it from overdrawing.
Then I installed the PSU into a freshly-built test box with a Winfast motherboard, Sempron 2600+, 1 GB of RAM, a GeForce 6200, a Turtle Beach Santa Cruz sound card, a PATA hard drive, and a PATA CD-ROM drive.
I used OCCT Perestroika in combination with Speedfan to measure the voltages while both idle and under load. For comparison, I also tested a Sigma Shark 635 W power supply on the same hardware.
The Zalman's 3.3V rail hovered around 3.28 V idle, and dropped during the load test. The ripple was 0.61%, fairly low for a mid-level PSU. However, it undervolted, and we here at ThinkComputers dislike undervolting a lot. The Sigma, though, rippled far less and overvolted, which is more acceptable than undervolting.
The Zalman's 5V rail (4.95 V idle) was much, much more stable, but still undervolted. It's within the 5% range that we like, though, and was immensely consistent. The Sigma, on the other hand, was inconsistent at times, but was closer to the 5V and undervolting, too.
Last, but not least, the 12V rail. Idling around 12.15 V, the Zalman overvolted and spiked a little bit here and there, rippling 0.49%. The Sigma, however, was solid at 11.97 V through the entire test.
The power supply is far quieter than any I've used thus far. The heat sink must really help with keeping the noise down!