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SLI & +12V

Last response: in Graphics & Displays
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January 25, 2012 5:36:08 AM

Ok so I've had some problems with my SLI setup (two EVGA GTX 570's). When playing Battlefield 3 my game seems very choppy sometimes for having two 570's running it. When I ran a single GTX 570, it ran smooth. I've been searching around the internet and tried many suggestions with no luck. So I finally decided to just call EVGA and ask them what the problem is. The guy that helped me asked about my PSU (which is an OCZ-ZX850W). He said the wattage is fine, but the +12V rail doesn't provide enough Amps for both cards. Each card requires 38 Amps under load, bringing it to a total of 76 total Amps needed. My PSU does a maximum of 70 Amps on the +12V rail.

I guess my question is, will I really see a difference if I get a PSU that has more than 76 Amps on the +12V rail. He also told me it doesn't matter if its a single rail or multiple rails, as long as the overall amps are more than 76.

I've been told this is micro-stuttering, is there a fix? Or did I waste $350 on another GPU? Also, people in other forums asked other questions like my resolution and my other parts. I have a single monitor with 1920x1080 as the resolution. Below are the other parts in my build.

i7-2700K (not overclocked)
Asus P8P67 Pro (rev 3.1)
8Gb Corsair Vengeance
OCZ-ZX850W PSU
OCZ 120Gb Agility 3 SSD
Western Digital 320Gb HDD
x2 EVGA GTX 570 (model: 012-P3-1573-AR)

More about : sli 12v

January 25, 2012 7:54:17 AM

I think 2 570s would use 38A under load. They use 2 x 6 pin PCIE connectors from the PSU that can supply max 75W eaxh + 75W from the motherboard = 225W each /12V = 18.75A max each and thats only if they take 100% of the power they possibly can. Do you have issues with any other games?
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January 25, 2012 8:19:13 AM

Nvidia have a list of all certified SLI PSUs
Link: Nvidia SLI Certified PSUs
By this link I posted, your OCZ-ZX850W is a certified PSU for 2-way SLI GTX 570.

So, 4 possible problems:
- Your other VGA have some problems (try it alone)
- Your PSU have some problem (don't now how to test it)
- Yes, it's micro-stuttering... (can't do nothing)
- You upped too much the graphic settings so your VGAs are running out of memory (try to follow up the memory usage using MSI afterburner and report here the results)
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