tips, tricks, and tidbits for GPU crunching

[WhiteFireDragon]

ok i'm just going to double post. i think an AX 850w will be fine, but i'll post a few numbers and let you decide on it.

i still didn't make the thread on 60w power saving yet, so for now you'll just have to take my word on it haha. this was done on a gtx480 when i had it for almost 2 weeks. i noticed that the machine would consume less power at night than in the day. i also took note of the power consumption right as it started crunching, and about 15 min into it. power consumption steadily rises, and it made me wonder why.

when i did my test, i think i used furmark and forced the fan to run at only 30% until it burned up to 100C, took power consumption readings at intervals of a few seconds. to let it cool, i turned off furmark and put the fan at 100%, and took power consumption readings at intervals of a few seconds. i repeated this loop several times, and it was pretty consistent within a few watts. after subtracting the power consumption of the GPU fan at 30% vs 100%, the gtx480 at the coolest point had a difference of about 60w than at 100C.

here's a few more power consumption figures. my TDP references came from this wiki page. here's some numbers for a gt240. load is either from WCG and/or GPUgrid

with dedicated GPU present
140w GPU + CPU load
107w GPU load only
112w CPU load only
75w no load

clarkdale IGP, no dedicated GPU
102w CPU load
65w no load

here's my analysis of it. based on no load from both, the GPU adds 10w (75w - 65w) just being in there, idle. you can also see that the CPU takes 37w (102w - 65w, and 112w - 75w) when it's loaded, and these numbers look accurate because both numbers with the GPU and without the GPU agrees. based on the difference between the load with GPU+CPU and CPU only, the gt240 takes about 38w (140w - 102w). this is probably accurate within a few watts because of the resolution of the kill-a-watt, or the way BOINC puts load on both the projects. with a higher efficiency PSU, you may shave off a few watts, but if you're overclocking, it may also add a few watts. i measured a few more GPU's with this method in the exact system. here's the calculations:

gt240 TDP: 69w
system consumption: 140w
GPU consumption: 38w, = 55% of of TDP

gtx295 TPD: 289w
system consumption: 272w
GPU consumption: 170w, = 58.8% of TDP

gtx275 TDP: 219w
system consumption: 225w
GPU consumption: 123w, = 56.1% of TDP

edit- poppageek's gtx460 similar power consumption results:
gtx460 TDP: 160w
systems consumption: 294w
GPU consumption: (294w system - 219w CPU load + 14w GPU idle) 89w, = 55.6% of TDP