850 Watt PSU Enough?

[acsdog]

I currently have a CX750M PSU, and using a Kill-A-Watt meter I see that in-game, I use about 650-700 watts. This is with 2 780's (SC) and an i5-3570k OC'd to 4.5 GHz.

Now I recently realized why my GPU overclocks were always unstable, even at +10 MHz; there is an overboost function in PrecisionX that adds a voltage boost.
I decided to test it out with a generous +150 MHz base clock and +350 memory clock. This is with the CPU overclock as well. I ran the Metro LL bench and got a good 14-18 FPS increase. Problem was, I looked at my Kill-A-Watt meter and saw 785 watts. I killed the bench and turned off the GPU OC, thankfully my computer didn't go up in smoke.

So what I'm wondering is, is an 850 Watt PSU gonna be enough? I plan on overclocking possibly further as my 780's get older, and I want some headroom. I also don't want to spend an arm and a leg for a 1000 watt PSU.

 

[i7Baby]

RealHardTech recommends 850W for a PC with gtx780 SLI.

But get a good one - from tiers 1 or 2 of http://www.tomshardware.com/forum/id-2547993/psu-tier-list.html#xtor=EPR-8886

eg http://pcpartpicker.com/part/evga-power-supply-220g20850xr

 

[FelixVincent]

If your budget allows get a slightly bigger psu but if not then go ahead 850w should be sufficent (judging by what youve shown here). If I were you i would also consider upgrading your gpus to a 900 series card becasue they overlcok like gods and have supper good power consumption.

 

[4745454b]

Keep in mind a kill a watt measures what's being drawn. If it's drawing 785W and we assume because it's at the top end of what the CX750 can handle its only 82% efficient, this means the system is using ~644W. This is within it's output abilities. An 850W might be a better idea if you want to OC more as long as it's a good 850W.

 

[acsdog]

I found the Rosewill Capstone 1000m for $129, it's rated 80+ Gold and has pretty good feedback. It is a bit overkill, but better safe than sorry.

 

[ko888]

For a system using two GeForce GTX 780 graphics cards in 2-way SLI mode NVIDIA specifies a minimum of a 850 Watt or greater system power supply that has a maximum combined +12 Volt continuous current rating of 60 Amps or greater and that has at least two 75 Watt 6-pin and two 150 Watt 8-pin PCI Express supplementary power connectors. (Minimum system power requirement based on a PC configured with an Intel Core i7 3.2GHz 130 Watt TDP processor.)

Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Sufficient Total Combined Continuous Power/Current Available on the +12V Rail(s) is the most critical factor.

Overclocking of the CPU and/or GPU(s) may require an additional increase to the maximum combined +12 Volt continuous current ratings, recommended above, to meet the increase in power required for the overclock. The additional amount required will depend on the magnitude of the overclock being attempted.

The conversion efficiency of the CX750M at a power draw of 700 Watts AC is 84.5%. That equates to a system power draw of 592 Watts DC.

 

[Dark Lord of Tech]

https://pcpartpicker.com/parts/compare/evga-power-supply-120g21000xr%2Cevga-power-supply-220p21000xr/
Great deal on the P2.

 

[i7Baby]

I found the Rosewill Capstone 1000m for $129, it's rated 80+ Gold and has pretty good feedback. It is a bit overkill, but better safe than sorry.

The evga850 G2 I linked to is $118.