Power usage of a 6970?

V

variant

Gawd
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Feb 17, 2008
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What is the maximum wattage of a 6970? I am looking to run 3 of them in crossfire and trying to decide what power supply to buy.
 
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TDP is 250w per card.

I'd get at least a GOOD 850w PSU to power 3 of them. To be safe I believe a 1000w would be best so you can overclock the cpu and run lots of fans and hard drives.

Corsair AX1000 would be a good bet for you.

With that said ask a mod to move this to the PSU sub-forum and see what the pros offer up.
 
With Powertune at default 0%, it'll use 250 watts. If you adjust it all the way up to +20%, it'll use up to 300 watts. You can also use a negative Powertune setting to limit the power usage to 200 watts, but with a performance hit.
 
If you overclock you cpu and gpu's , I'd go with a 1200 watt psu. If your overclocking the cpu but not the gpu's , a 1000 watt psu will do.
 
variant said:
Isn't that overkill if each card is 250 watts? I can't imagine a processor, sound card, and drives eating up 400 watts.
Click to expand...

Growth is a factor. When you are spending high amounts on a 850 w psu + in size you need to expect increasing hardware growth. You may make a mistake getting just enough. As cards are getting newer and faster and new pcie buses come out they are consuming more energy.

Secondly look at my signature system below. I pull 1.1kw from my UPS with nothing else plugged in. These cards draw more than you think. Tdp is like a stealership trying to sell you a car based on a sticker that sais 35 mph. That is once you buy it you learn how much more gas it actually burns. Like I said Tdp looks good on a piece of paper.
 
The other thing to consider is that using a higher wattage PSU than what is necessary for all of the components in the system, allows the PSU to operate further down its efficiency curve, where it peaks with a higher efficiency.

Typically, most PSUs have their highest efficiency around 50% of rated load. The farther you push them to their rated max total output, the worse their overall efficiency is.

In any case, my personal preference is to buy the biggest PSU I can then never have to worry about having enough juice for whatever you want to use. The extra headroom is worth it.
 
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