With my trusty auto-ranging Radio Shack multimeter I deduced the following info...

DP Pentium D

• Idle: 188W
• Playing HL2: Peak: 305...average 280

Energy cost:

At California's 22.1 cents/kWh, power costs $0.164 per month per watt.

Note, this is using my multimeter, measuring AC amps and multiplying by 120.

Device	Power Usage	Monthly 24/7 Operational Cost
ADI MicroScan 19" monitor	102 Watts	$16.73
Planar PL-201M Flat panel display	48 Watts

Old Pentium 166 Overclocked to 200 Mhz

Pentium 200, no Hard Drive	33 Watts	$5.41
Pentium 200, 8GB Hard Drive	38 Watts
Pentium 200, 120GB Western Digital WD 1800 Drive	40.8 - 42 Watts

Notes:

• The WD 1800 specs on the sticker say it's rated to .8A @ 5V and .45A @ 12V or 9.4W. On the website, they claim it's 7.5 Watts idle, and 7.75 during read & write. On the P200, I measured between 7.8 and 9 Watts. This means my measurements are at least in the ballpark. This is a 7200 RPM, 180 GB drive.
• The Seagate ST3200822A I'm thinking about replacing it with claims to use 7.5W Idle, but up to 12.5W peak. However, this is a MUCH quieter drive. The WD does 35 dBA in idle mode, the Seagate is 25 dBA.

PIII 700, 40 GB Hard Drive	51 Watts
PIII 700, 40 GB Hard Drive, playing an audio CD	54 Watts
PIII 700, 40 GB Hard Drive, ripping an audio CD	63 Watts

Lancewood Machine

This machine has a Dual PIII, slot 1 motherboard. I've noticed that the PIII, unlike the P... well, P1 (PI?) seems to trim back its power once the OS is loaded. Perhaps this is Linux using its low power noop thing. Anyway, I don't really about pre-boot power as the machine spends no time at that point. However, I do use it to measure HD power usage.

The machine with 1 proc installed eats up about 54 Watts without the HD, and 60 Watts with it after it's spun up. Therefore, I'm assuming this drive eats up 6 Watts, which is reasonable.

Two 1Ghz procs, 10k rpm SCSI, idle	46.8 Watts
One 1Ghz proc, 10k rpm SCSI, idle	42 Watts
One 1Ghz proc, 10k rpm SCSI, running openssl speed	57 Watts

(with the iPark tool - all prior measurements were with my mulitmeter. NOTE that they actually jive almost perfectly!)

Two 1Ghz procs, two 7200 RPM drives, idle	48 Watts
Two 1Ghz procs, one 7200 RPM drive, idle (or playing music)	42-45 Watts
ditto + switch, wireless modem (my whole closet), idle	60 Watts
ditto, running 1 openssl speed	80 Watts
ditto, running 1 openssl speed	102 Watts

openssl output (virtually the same if you run 1 or 2 procs)

                  sign    verify    sign/s verify/s
rsa  512 bits   0.0014s   0.0001s    729.6   7905.7
rsa 1024 bits   0.0068s   0.0004s    146.9   2775.3
rsa 2048 bits   0.0407s   0.0012s     24.6    834.7
rsa 4096 bits   0.2732s   0.0042s      3.7    237.7

Notes:

• Drive power usage seems to spike when the drive has been idle by 18 Watts, then settles back down to 6 Watts more than idle
• According to this, the 1Ghz PIII should dissipate a maximum of 26.1 Watts. When stressed by OpenSSL, we see a 18 Watt rise for 1 proc. It costs us 4.8 Watts to add a second processor. So, that sort of adds up; 4.8 + 18 = 22.8 which isn't that far from 26.1, allowing for a safety margin.
• If that's true, then for the idle case we have...

(42 Watts total) - (4.8 Watts Processor) - (6 Watts hard drive) = 31.2 Watts ...31.2 watts of power supply, LAN, Video card, memory and other junk to keep powered.

• The iPark tool and my multimeter measurements come out essentially the same
• Almost seems that either the Lancewood motherboard and/or the Western Digital drives are more power efficient than the Soyo desktop board and Maxtor drives
• Playing mp3's (streaming the audio files from the drive and playing it through the sound card) consume virtually no power!

-- MattWalsh - 06 Feb 2002