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SLI GTX 680, 750 WATT PSU?

Last response: in Graphics & Displays
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September 1, 2012 7:14:06 PM

Hey guys, I posted a question about my gpu usage dropping and fluctuating ( goes from a very good fps 90-99% all the way down to a 60-65% with poor fps)
and i forgot to post that I am using a 750 Watt Antec gamer extreme PSU which says its SLI enabled......
Is this enough watts and maybe, is this the reason for my ever changing GPU usage?????

thanks, and just for everyone to know i dont think my gpu is throttling down as im keeping it under 70 degrees in the 1st place.
Any help would be greatly appreciated, Im using MSI Afterburner to keep track of my stats.

2 x GTX 680's (reference) PNY
Nvidia surround enabled 5760 x 1080 resolution
SLI enabled
September 1, 2012 7:26:10 PM

An HX series 850W from Corsair is more than enough for a GTX 670. So two 680s would probably need about 850 or more, just to be on the safe side.

By the way your set up sounds really cool :) 
a c 212 U Graphics card
September 1, 2012 7:37:10 PM

i'd have used an 850 watter, especially if overclocking them .

http://www.geforce.com/hardware/desktop-gpus/geforce-gt...

There you'll see that nVidia calls for 550 watts for the system + 195 watts for the 2nd card....that's 745 watts

But here's you'll see that the power draw in SLI is < 500 watts ... w/ 173 watts per card
http://www.guru3d.com/article/geforce-gtx-680-sli-revie...

Guru 3D recommends the following

Quote:
Here is Guru3D's power supply recommendation:

GeForce GTX 680 - On your average system the card requires you to have a 550 Watt power supply unit.
GeForce GTX 680 SLI - On your average system the cards require you to have a 750 Watt power supply unit as minimum.


Overclocking adds about 24 watts per card or 50 watts, so while I'd say ya safe with the 750, I'd be more comfy w/ an 850

http://www.overclockersclub.com/reviews/nvidia_gtx680/1...
a c 236 U Graphics card
September 1, 2012 7:42:52 PM

Your psu is a good one.
Because it has (4) 6+2 pin leads, it will be able to deliver the needed power to all your cards.
A 6 pin connector can deliver 75w. 4 of them is only 300w. Add the 75w that each pci-e slot can deliver at maximum, and you are still using only a maximum 450w out of your 750w psu for the graphics cards. All the rest of your system probably does not need even 150w.

One possibility is that the graphics cards are loafing when fps demand is low and may be reducing it's performance to save power.
In the Nvidia control panel/3d settings/ try setting the power mode to prefer maximum performance.
!