OCZ 850w Power supply run 4870x2 crossfire ?

[jamieuk23]

What do you recon ? would only have 1 hard drive in my PC as well. Hopefully it

[antiacid]

yes, it will work just fine.

[jamieuk23]

If I am honest I thought defo NO! as I have read that it needs 1000w to run. is it because I am using a good brand of power supply why it will.?

[Vienna]

850Watts, depending on the rest of your system is *pushing it*, its right on the edge. That's assuming a 100% load all the time, if your like most people, and only load your GPU's, say 20% of the day, then 850 is plenty.

The reason its pushing it, is depending on the rest of your system, IF you put a 100% load on EVERYTHING(HDD, CPU, GPU's, RAM, etc) your going to be hitting close to 850Watts. Most people go with bigger PSU's not because they NEED to, but because they like that extra overhead. Frankly, under normal gaming stresses I doub't you'll hit more than 600-700watts with dual 4870X2's crossfired.

[STEvil]

600 is pretty easy to do with a single 4870X2 if you've got a high clocked CPU.

[antiacid]

If I am honest I thought defo NO! as I have read that it needs 1000w to run. is it because I am using a good brand of power supply why it will.?


I run a q9650 @ 4.2, a wc loop, 2 hdd (1tb wd black, 300gig velociraptor), 1 dvd writer, 6fans, a 4870 1gig and a 4870x2 2gig in trifire and my ram/cpu/gpu are all overclocked and I have no issues whatsoever with a zalman zm-850 psu. The "reason" people buy big PSU is because:
1- you want overhead in case you upgrade
2- you want overhead in case there is a spike in demand
3- you want overhead so that you fall in the 50% range of the PSU to get better efficiency out of it (a PSU is more efficient at moderate loads/temps than at high ones).
4- It sounds nice in a conversation to say you own a thousand watt power supply to power your computer (which basically makes people think about appliances or microwaves :P)

So in conclusion, based on my own experience, a 850watt psu is enough for a single 4870x2, a mildly oc'ed cpu and a single hdd like in your configuration. When I get home, I'll look at my UPS to get an estimate of the power consumption when I run everything at the max.

[Kensek]

I use a Corsair HX1000 for my 2 HD4870X2s at OCd to 852/1000 and an i7 965 at 35x128 (4.48 GHz)

When running Vantage and 3DMark06 Kill-a-Watt will report a Max Draw of 838 Watts during the intensive parts.