Originally Posted by lenngray
I just measured my old Phenom-9600 XP computer and my newly built much faster W7 one with a Kill-A-Watt power-meter. The XP only has "standby", which leaves fans and its 3 disks and who know what-all running, and only cuts its full-on power use from 111 Watts down to 83 Watts (excluding monitor). The W7 machine is an FX8350 on an ASUS M5A99FX with 8GB RAM, a single Drive, and a fairly good NVidia graphics card, and its true "sleep" mode cuts the running power of 70 Watts to (count-em) TWO!!!! It apparently keeps only the memory refresh powered up during sleep.
I read someone's claim that computers drew 50 Watts when literally OFF, and that's totally wrong. Even my XP machine only registers 3 Watts when "off", and that's through a surge protector.
- Lenny - (an actual Electrical Engineer and long-time computer guy)
The reason your XP computer uses so much power in standby is because it is using S1 sleep, which leaves the PSU on, and only puts the computer's components in low power mode. Computers nowadays use S3 sleep, which actually turns everything off, except for the memory, USB power (in some computers), and LAN devices (usually if wake-on-LAN is enabled). Hibernation is perfectly identical to power off as far as power consumption is concerned.
S3 sleep has been around for a long time, so I would be surprised if your XP computer doesn't support it. Make sure that S3 sleep is enabled in the BIOS and that your video driver is good (not running the generic Microsoft VGA driver).
Typical "off" power draw for a computer is 1 to 10 watts, with the majority of that usually coming from unneeded or wasteful components in the PSU. S3 standby typically adds another 1 to 10 watts to that, depending on the motherboard and memory.
Edited by Techie007 - 5/14/14 at 8:58pm