Friday, October 15, 2010

Dell Precision 690 Power Usage

I recently got an old P690 workstation for home and have been a little curious about its power consumption. They don't seem like very energy efficient systems so I borrowed a watt meter and took some measurements in various states.

The specs for the machine I'm testing:
Dell Precision 690 (750W PSU)
2x Intel Xeon 5160 @ 3.00ghz
ATI FirePro V3700
4gb FB-DIMM (2x1gb, 4x512mb)
Windows 7 Ultimate X64 (fully up-to-date)

And here are the results (note that "low power mode" was enabled, and wake-on-lan was disabled in the BIOS):

Power off: 22w
Power on/idle: 198w
Power on/prime95(small fft):  312w
S3 Sleep: 22w

The power on usage is around what I'd expect, but the off/sleep usage is a little high. I've heard FB-DIMMs are quite power hungry, so let's try removing some and testing with 2x1gb, also I decided to test S1 sleep too:
Power off: 22w
Power on/idle: 162w
Power on/prime95(small fft): 275w
S1 Sleep: 178w
S3 Sleep: 22w

So power on usage has dropped by around 35watts, that's quite a lot of power for 2gb of ram! But what's this? S1 sleep actually consumes more power than normal power-on mode... Maybe speedstep isn't used when in S1 sleep mode? Maybe there's a bug in the BIOS? Who knows, but it seems like a useless sleep state.

Well there you go, not too many shockers, but at least all this explains why the RAM gets so damn hot :P