5870 & 5970 Full Load Power Consumption

[Cablesaurus]

Doing some comparisons and I'm trying to find a good standard rule of thumb on how much power a 5870, and a 5970, would each use under load? I understand an 850w PSU would run 2 5970's, would that also run 4 5870's?

[sc8nt4u]

P = V^2/R

[Raulo]

850W for 4x5870 will probably also be sufficient short term but you will be running at very close to nominal PSU wattage. And loading the PSU so much for an extended period of time is not going to be good for its longevity.

[JollyGreen]

It looks like about
300W for peak power of a 5970
200W for peak power of a 5870
I've seen estimates of around 150W peak power for just the mobo/cpu

850W would be borderline for two 5870 and a 5970

[burtyb]

Here's some "real world" values when adding HD5870 to one of my boxes with PSU1(305W)=MB/drives/etc, PSU2(650W)=PCIe power (measured via Dominion PX).

With 0x5870 - PSU1=68.5W (102.6VA) (onboard graphics only so no PSU2)
With 1x5870 - PSU1=120.8W (172.4VA), PSU2=138.0W (181.9VA)
With 2x5870 - PSU1=158.0W (208.2VA), PSU2=286.9W (361.1VA)

[qed]

The P=V*I or P=V^2/R are not really usable here. Have a look on the web for real data, or even better by yourself a kill-a-watt power monitor (Watt not kWh). Are very cheap and usefull.

My system is an i7 920 + 2x HD6950 Crossfire:
Idle: 168W (monitor included)
Full load: ~500W

Keep in mind that the power drained from the socket, the ups will have something around 85% efficency.

[cdb000]

Doing some comparisons and I'm trying to find a good standard rule of thumb on how much power a 5870, and a 5970, would each use under load? I understand an 850w PSU would run 2 5970's, would that also run 4 5870's?

In my attic I have 8 5870s divided over 3 machines.

All are clocked at 945MHz - about 11% over standard clock.

The total power use, at the wall socket, is 1900 Watts, so slightly under 240W per card of mains power.

Assuming the power supplies are 85% efficient, and ignoring power use for CPUs, HDDs, chipsets, each 5870 might be estimated as using slightly over 200W.

This crude approximation suggests that your 850W power supply can probably run 4 5870s, but you would be very close to its maximum output, particularly if you overclock the cards.

[someotherguy]

Good 1200W power supplies can handle sustained 1350W load. I'd guess that good 850W PSU's have some reserves too.

The power can get a little "messy" when ever over the nominal load limits for sustained periods of time on most power supplys.

[fornit]

power supplies deliver less and less energy over time. and they age faster when they constantly have to supply too much power. so in my opinion, a suitable power supply is a good investment.