Power consumption

chameleon · 13 May 2008 at 02:42

How much power does a PC actually use? As in, whats the current draw at the mains plug? I have been getting GBH of the earhole regarding the rather high electricity bill and was wondering if running my PC for a large chunk of the day has anything to do with it? I have an Enermax Infiniti 720W PSU and an Intel E6420 cpu and 8800 GTX graphics card. The system seldom works really hard, WOW runs the cpu at 50-60%. Also is there any current draw when the system is on standby as the PSU is still on even if the rest of the system isnt?
So how many amps would I be pulling?

split · 13 May 2008 at 03:09

Have a look in this thread.

You can buy a device to tell you, and maybe it's using some when you dont think it is.

Nemek · 13 May 2008 at 08:25

I was under the impression that it was like if you had a 600W PSU your pc would use 600W whether it needed it or not, same as if you have a 1000W your pc would use 1000W. i maybe wrong however thats what ive been told before.

Nick644622 · 13 May 2008 at 08:52

No, the Wattage on the PSU is the maximum it could supply, in a similar way to a 100BHP car engine doesn't produce 100BHP at tickover, only when you floor it. The PSU will only take from the mains what the PC requires (+ a tad)

chameleon · 13 May 2008 at 11:16

Plus I think 720Watts@ 12 or 5v is going to draw less from a 240v mains isnt it?

Janesy B · 13 May 2008 at 11:23

chameleon said:
Plus I think 720Watts@ 12 or 5v is going to draw less from a 240v mains isnt it?

No, you can draw 720W through a 12V supply, ie if you are using 50Amps at 12V, you will be drawing 600Watts plus a bit more for the PSU to generate that amount of power (very unlikely scenario).

gt_junkie · 13 May 2008 at 11:24

My old pc with an overclocked 3870X2 and overclocked e6600 (3.4ghz) Only pulled 327 watts at full load. Just under 200 watts idling.

I had an 850 watt psu at the time and felt it to be overkill.

I sold it and bought a 550 watt fanless PSU which now happily runs my PC in sig. Funny thing is that Nvidia recommends a 600 watt psu minimum for the GX2.

gt

Janesy B · 13 May 2008 at 11:28

gt_junkie said:
My old pc with an overclocked 3870X2 and overclocked e6600 (3.4ghz) Only pulled 327 watts at full load. Just under 200 watts idling.

I had an 850 watt psu at the time and felt it to be overkill.

I sold it and bought a 550 watt fanless PSU which now happily runs my PC in sig. Funny thing is that Nvidia recommends a 600 watt psu minimum for the GX2.

gt

its always good to have a bit of overhead. once you start hitting the limits of the PSU you will get voltage drops on the rails, it will become a lot less efficient and may even burn out the PSU

gt_junkie · 13 May 2008 at 11:33

Janesy B said:
its always good to have a bit of overhead. once you start hitting the limits of the PSU you will get voltage drops on the rails, it will become a lot less efficient and may even burn out the PSU

I know - but when the power usage of my PC in sig at full tilt is around 350 watts i'll still be 200 watts off the PSU's maximum capability.

With the 850 i would have had around 500 watts of 'overhead' which was more than i can reasonably justify.

Corsair ran an 8800GTX SLi set up off your 620 watt PSU. Just shows how little power standard gaming PC's actually use.

gt

james.miller · 13 May 2008 at 11:33

chameleon said:
How much power does a PC actually use? As in, whats the current draw at the mains plug? I have been getting GBH of the earhole regarding the rather high electricity bill and was wondering if running my PC for a large chunk of the day has anything to do with it? I have an Enermax Infiniti 720W PSU and an Intel E6420 cpu and 8800 GTX graphics card. The system seldom works really hard, WOW runs the cpu at 50-60%. Also is there any current draw when the system is on standby as the PSU is still on even if the rest of the system isnt?
So how many amps would I be pulling?

my old pc drew 384 watts from the mains under full load.

e6600 @3.2ghz
2ghz ddrII
8800gtx @ stock
7300gt
xfi gamer
two 18x dvd writers
360 hd-dvd drive
two 500gb hdd's, one 250gb
imon ultrabay vfd
all-in-one card reader
corsair HX 620w psu

and that 384 included the draw of the 22" dell monitor i had at the time. iif you take away about 30w for the monitor (i cant remember how much it actually drew), and then factor in an 83% efficiancy (about right for that psu driving that load) then the draw of the component on the psu actually came in at under 295w. ie, nowhere near as much as people like to think. exactly why a 620w psu is quite capable of powering 2 8800gtx's, even though its not nvidia certified and people try to tell you otherwise.

shadowscotland · 13 May 2008 at 14:48

In total agreement with the two james above - 550w is more that enough for any Xfire SLI machine. and 400w is fine for single card solutions aka everything else.

The antec earthwatts 380w psu is the lowest wattage i'd personally go with an atx supply as it's really hard to find a retail 80plus certified unit below that. (matx and power brick's not inc)

Edit: but back to the OP topic - the E6420 are little low power/heat gems, so about 125w idle, 250w gaming. (presuming you don't have a 300w soundsystem linked up)
if gameing 4h a day + idle 12h + off 8h
(4*250) + (12*125) + 0
1000 + 1500
2.5kwh per day or ~30p or £10 a month. (12p a Kwh)

if G=5H I=19h - £13 a month

but if your bedroom has a tv + ps3 + stereo + pc + lamp + mini fridge Etc your room could be 4x that!

MikeHunt79 · 13 May 2008 at 15:23

chameleon said:
So how many amps would I be pulling?

Between 1 and 1.5.