Post
by QUIET! » Tue Sep 01, 2015 6:13 pm
For an X99, the motherboard, CPU (130 watt TDP?), ram and SSDs probably use around 160 watts when heavily stressed. The GTX980s probably pull less than 200 watts each when heavily stressed so your full load is around 560 watts but probably more like 400-500 in heavy use (it's unusual to fully stress everything at the same time). Your PSU is more than you need, if it's not quiet, that might be a place to improve with a 650 or 750 watt 80+ gold or platinum.
The rest is fan control and the case.
If your PSU is making noticeable noise, I suggest buying a Kill-a-watt to see how much draw is at the plug, then go to plug load solutions to find the 80+ report with your efficiency curve to see what the actual DC load is like and then go shopping for a PSU with an appropriate rating. You should use stress testing software to find your maximum draw and then some gaming or whatever you use those GPUs for to find a typical draw. If there is a big gap between maximum and typical, I would go for about 110% of maximum or about 180% of typical, whichever is higher. If the gap is closer, 125% of maximum would probably do it.
When PSUs are tested, they usually can put out 105-110% of their rated power without popping. If your maximum is a lot higher than typical, it should be able to handle 90% output on the odd occasion that you stress test it or start using software that is stressful, while a typical load is 60% or less than the rated power.
If the gap is close, running at 75-80% will give you enough reliability, efficiency and excess capacity.
Running a computer with a typical load much less than 50% of the PSU rating is usually very inefficient at idle which means more heat and more noise typically when you want it to be as quiet as possible.
On the other hand, I like socket 115x stuff, modified 230 watt Dell 80+ gold ~ATX PSUs and idle power less than 30 watts (at the plug) so you are near the opposite extreme.
For my example, I got 23 watt idle, 177 watt load (Furmark or something) and about 120 watts gaming with a 230 watt PSU, so 10% idle, 45% typical load and about 70% at maximum load so the PSU is rated about 190% of my typical load, and about 135% of my maximum. That seems just about right to me, 200 watts would be fine but it's hard to find anything 80+ rated with wattage that low.
In your example, there are plenty of PSUs in that power range, enough that you could get picky about wire length and still find something that will work. My Dells need a little cable surgery to hook up to GPUs and reach across the case.
