Power Consumption of a Typical PC While Gaming

cliffski writes "How much does your PC really draw in terms of power when idle, when in sleep, and when playing a demanding game? I don't trust everything the manufacturers of hardware say, so I thought I'd get myself a watt measuring device and run a few tests on some of the gear I leave on all the time, and the gear I go to the trouble of turning off. The Linksys router drew 8 watts, the monitor drew a fairly noticeable 30-31, but what surprised me was how little power the base unit drew, even when playing Company of Heroes. Also, the variance of power draw for Vista seemed minimal, regardless of what you got the machine to do."

Comments

Re:What about my A/C kicking into overdrive?

[mr_mischief]

Any decent electronics project book will verify that any copper or aluminum wire will gain resistance with increasing temperature.

If you want a quick link, though, how about this article at Dan's Data about power supplies which actually gives some basic theory? It's a little suspect in that it's a review of a particular brand of power supply, and Dan's Data isn't as widely known as Tom's Hardware or Anandtech. What do you want from the very first Google result for the search "warmer power supplies draw more current", though? It also happens that he's right (about the issue, anyway -- I've never reviewed or purchased Topower power supplies).

Re:Little information

[cliffski]

Hi. Theres a single hard drive in there. a typical 'shipped with the box' PSU, no wireless card or anything fancy.
The PC is from mesh Computers, about a year old.

Re:I love kill-a-watt

[ivan256]

I can hardly believe that the router mentioned was using 8 watts, what is the time period there? I know the power supply on my linksys router is in the milliamps so, basic conversion would indicate to me that is not possible. I am probably thinking of something backwards though. Time is a component of the "watts" unit. One watt is one joule per second. So the time period is irrelevant.

8 watts at 120 volts (simplistically speaking) would only be about 66 milliamps.

Re:Consoles

[CastrTroy]

Here's a comparison that shows XBox 360 vs. PS3 vs. Wii vs. PC in many different areas including standby, idle, gaming, and movies (Wii not included in movies).

Re:What about my A/C kicking into overdrive?

[Macman408]

Typical air conditioning can remove heat from your house with a 30-45% penalty; eg running a 100W appliance might cost another 35W in air conditioning. Incidentally, at least for air conditioning planning, I've seen a human listed as producing about 600 BTUs per hour, or 175 Watts. So your room might be warming up as much from you using the computer as it is from the computer itself.

Also, some people seem surprised that their computer has a 450W power supply even though it is only drawing 150 Watts. This is because a power supply needs to supply the peak power for all accessories that might ever be installed. If you buy a computer from Apple or Dell, the power supply needs to have enough capacity to handle not only what you're getting, plus power for extra hard drives, PCIe cards, USB devices, FireWire devices, and anything else that might be added later. Furthermore, the power budget that they work with during design likely takes into account the maximum power specified for every single chip on the motherboard, even though it is unlikely that any one of them could reach that limit, much less all of them at the same time. The CPU's specifications might require 80W, even if it's only for a few milliseconds, and for the worst combination of operating temperature, manufacturing variance, and CPU load. There's a large margin built in to the design to ensure that your computer's power needs won't exceed what can be supplied.

In my case, my Dual 2.7 GHz PowerMac G5 has a 600W power supply, even though the peak usage I've measured is around 250W. Another 90W or so is reserved for PCI/PCI-X slots that I don't use, plus there's capacity needed for another hard drive, and 4 more sticks of RAM. Add in 15W available for bus power on FireWire, 2.5W for USB bus power... Then there's the difference between the actual sustained peak usage and the specification's instantaneous peak usage, which increases the requirements significantly. Pretty quickly, it adds up to something pretty close to 600 Watts.

I borrowed a Watts Up meter from the local library (the local power company supplies them to area libraries). I'd suggest that those interested in learning about their power consumption check if there is a similar program in your area, or ask if the power company, library, environmental group, or other organization would be interested in starting one. Or, offer to buy one and donate it when you're done, and encourage others to do the same.

Power consumption of PS3 / Wii / XBOX 360

[IYagami]

You should take a look at http://www.hardcoreware.net/reviews/review-356-1.htm

This is the main information:
Power Consumption in Games
PS3: 185.9 Watt average
XBox360: 176,54
PC (see link for more information): 156,6
Wii: 16.8

Re:What about my A/C kicking into overdrive?

[mollymoo]

So does your computer, powersupplies get less efficeint the warmer the room is. So while your useing only 200 watts, at 70 degrees, at 85 degrees, it's probably past 250.

Resistance does increase with temperature and a thermally controlled fan will spin faster and draw more current. But enough for a 25% rise in consumption from a 15 degree (in unspecified units, I guess you mean Fahrenheit) temperature rise? That's seems like a hell of a lot for a fairly modest rise in temperature.

For an 80% efficient power supply, an increase of 25% overall consumption is more than double the power loss. The reality is very complex, but we can pick out a few relevant numbers to get a feel for the magnitudes involved. Empirical testing would be easier than an analysis, but here's some food for thought:

For copper, the resistance rises by about 0.4% per degree Celsius rise. Your roughly 7 Celsius rise would increase it by a whopping 2.8%. You'll have melted the insulation well before even a 50% rise in the resistance of your copper wire.

If you look inside a power supply, you'll see a big fat heatsink. Attached to that are rectifiers and switches - diodes and FETs. That's where a big proportion of your power supply's inefficiency comes from. Looking at the first power FET datasheet I have to hand (for a Fairchild HUF75337P3), the on resistance increases by something like 1% per degree Celsius rise. For diodes because the forward voltage drop actually decreases with increasing junction temperature - they get more efficient. For an International Rectifier 12CWQ03FN it looks to be about 0.2% lower per degree Celsius rise.

The YS-Tech 80mm fans in this box next to me consume 0.84W at full speed. That's a slow fan though, I wouldn't be surprised if more typical ones used 2-3W at full speed.

Hardly a complete analysis, but just can't see where you're getting this additional 50W from. I think you're out by an order of magnitude.

Re:Accuracy

[Quelain]

I don't think they are accurate at all on switch mode power supplies. I have one which is definitely wrong when measuring a PC PSU.

I think they expect to see peak current at the peaks of AC voltage, but a switch mode PSU will take small bites of current which may or may not coincide with the voltage peaks.