Power saving tipps for desktop PCs

Question

Hi, lately I've been trying to make my boxes at home (router, desktop, fileserver) more power efficient. My energy bill was always kinda high and I think that I waste too much energy.
Most of my experience with computer related power saving comes from my laptop (maximize batterie time ). I've already taken some steps to minimize power consumption but I'm not sure what else could be done. If you have some ideas please let me know!
Some details about the steps I've taken so far:
router (24/7)
Its an really old stripped down mashine (P2) that is underclocked (hard).
It's currently running pfsense (FreeBSD based) that is installed on an old hdd. I was thinking about getting a small usb-stick and running the system on that one... would that be a good idea? (lifetime etc)
fileserver
Runs only when needed. In addition the cpu is undervolted (ondemand). Should be ok I guess.
desktop (24/7)
This one is a bit more tricky. It has pretty much up to date (-> power hungry) hardware but needs to run 24/7 most of the time (ssh, ftp, p2p). Downgrading can only be temporary because sometimes I need the performance (casual gaming, video encoding, photoshop etc...).
So far I did only 3 things:
1. hdds go to sleep when they are not used for 15 minutes --> hdparm -S 180
2. cpu undervolting --> cpufreq-set -g powersave
3. grafik card underclocking --> nvclock -n 250 -m 350 (nvidia only)
I'm a bit frightened to underclock the grafik card even lower... my screen got blocky and froze once while testing. ^^'
2 & 3 are done with a small script that I run when I leave the pc:
#!/bin/bash
if [ "$(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor)" = "performance" ];
then cpufreq-set -g powersave && nvclock -n 250 -m 350 && xset dpms force off
else cpufreq-set -g performance && nvclock -r
fi
I've a shortcut for the script on my keyboard but some automation would be better if I think about it... triggered by afk time or sth like this.
If you guys have ideas what else could be tweaked please let me know!
Last edited by sen (2008-08-08 01:04:44)

Answer 1

Raccoon1400 wrote:Using a flash drive instead of a HD may save a bit. It may be significant, it may not, but every little bit would help. Flash drive would take much less power. Maybe several times less.
You could also check out solid state drives for the desktop. I know very little about them, so it may be a good or bad idea.
Yeah flash drives uses less power but I wouldn't use them for a desktop pc. The price per GB is far worse compared to normal HDDs and the blocks can only be written around 100000 times... for a system disk this is not really acceptable (caching, temporary files etc). These SDDs are more designed for small (sub)notebooks imo because they have no mechanical parts what makes them more reliable.
For the router this would not a problem though.
omgwtfbyobbq wrote:A stick would definitely be cheaper! The HD power draw isn't as low as I thought it was but it's close. The power supply can be a huge draw like I mentioned before. There's a 20W and 40W difference at idle between a earthwatts 380 power supply and a couple generic power supplies I had lying around. I originally though my PIII used way more than my C7-D system, but after swapping power supplies I found out the PIII used less at idle than the C7-D even w/ two sound cards, a network card, and a video card.
Yeah a quality PSU will probably save allot. Currently the router uses an old generic power supply, so this is really sth i should look into. I have an enermax noisetaker that is not used atm so I'll see what difference it makes compared to the currently used PSU.
The power consumption of HDDs is really not that low (thx for the link). Around eight watts (Idle) for the tested HDDs. So putting the disks to sleep when they're not used is probably a good idea for the most people that leave the PC running for longer times. My desktop has 5 HDDs, so even when they are not really used they need around 40 watts for nothing. Old HDDs (like the one in my router) will probably need more power.
I've asked a friend of mine to lent me his digital wattage meter. With this I can make some detailed tests to see what tweaks are really useful to save power.
I'll post the results when I'm done (probably on the weekend). What I can say now is that the few tweaks I made on my desktop PC (first post) will probably save a bit. The temperature of the CPU and GPU drops around 10-15 °C, the ambient temperature drops allot as well. This pretty heavy considering that the case has a good airflow (2 80er fans in front of the hdds and one 120er fan at the back).
Last edited by sen (2008-09-01 18:33:40)