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Bad SLI gaming performance. Need Help

Last response: in Systems
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December 27, 2011 10:20:42 AM

Hello all, i have a Computer that i built about a year ago. I had a GTX 460 768mb model in my built and so i added a another Gtx 460 768mb not so long ago.

I have all the latest drivers and updates.
I have latest BETA nvidia drivers

Here is my system.
AMD X6 1055t @ 3.3Ghz (with aftermarket cooler idles at 24 degrees under windows) says 40 under BIOS
8GB Ram 1600MHZ
MSI NF750-G55 motherboard
GALAXY GTX 460 768MB
EVGA GTX 460 768MB
1TB 7200RPM HDD
90gb SSD Corsair Force Series 3
950WATT rosewill PSU

so the problem is when i run Battlefield 3. With one card i can run the game at ULTRA settings no AA at 1680x1050 and i get about 30-35 FPS and the game is very playable.

When i add the other card for SLI i enable it under Nvidia control panel and i get about 50-60FPS but the game stutters alot. The game dips down alot to about 20-30FPS and then comes back up to 50-60fps. Making the game unplayable.

games like Bad company 2 seem to run fine under SLI i get 60FPS maxed out at 1680x1050 resolution and it never dips down.
With one card i get about 40FPS

Can it be BF3 or is there a bottleneck on my system.

I was thinking it may be my motherboard since it has and old chipset that was meant for DX10.
or can it be that i mixed different brands on the video cards. I do overclock both to the same speeds using EVGA Precission

i was thinking of getting this board http://www.newegg.com/Product/Product.aspx?Item=N82E168...
since i also have 90gb SSD Corsair Force Series 3

can anybody help me point out my bottleneck and what i should upgrade. i want to be able to play BF3 on ultra settings no AA and get about 60FPS with no stuttered.




a c 78 B Homebuilt system
December 27, 2011 1:05:28 PM

Stuttering is something that is particularly acute in 2x video card setups.

The problem is that your second card is always ready to render immediately after the first one, with a huge gap before the first card is ready to render again. Then the first one renders and the second one is again ready directly after with another huge gap until the first one is ready.

There is little you can do to counteract this effect except not using 2 video cards.

This is called Micro Stuttering and its very annoying. Please type "micro stuttering" in the search bar at the top of this website and it will point to a good article on the subject hosted by Toms Hardware.

The article describes potential things you can do to get around the problem, but it is primarily a hardware issue and as such you will likely have difficulty effecting change.

The two big fixes are 1 powerful card instead of 2 weak ones or to have a 3rd less powerful card to sit in the gap between the time the 2nd one renders and when the first one is ready to render again.

Nvidia has a program in their drivers that tries to smooth this out somewhat, but obviously it doesn't always completely mask the problem.

In any event, BF3 is a highly processor intensive game, you may want to try OCing your processor a little on the off chance that it will help somewhat, but don't hope for too much in this regard.

The tougher the game is on the graphics cards, ie the harder it is for the graphics card to render 1 frame, the more micro stuttering you will have, so the more you pump the settings the worse it is going to be.

I would try to take the 2nd video card back to the store for a refund. Tell them you bought it for somebody and they got another one for christmas from somebody else or something and maybe they will take it back. Then start saving for one of the new AMD 7000s or something else that will do well without x2ing.
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