Question regarding Crossfire / SLI GPU setups

So I spent the last weekend and the past several days trying to figure out WHY I get FPS drops left and right. Its mainly accustomed to when my dual GPUs (Twin Frozr III 6950s) drop their usage from 95%+ to around 50-60%. Now I tested some games and Heavenmark 2.1.

Heavenmark 2.1 - In a few scenes the GPU drops to 80% usage each. My overall score and max FPS are pretty much 2x what they are with crossfire disabled. Scaling has to be damn near 100%. Minimum FPS with 2 cards was 29 where 1 card did 23. FPS was also double I believe.

Metro 2033 - The GPUs are moving all over in this game. The game is beautiful and pretty fluid when they are rocking @ 99% but once they drop, the FPS goes into the lower 30s. I don't have too much information on this one.

Crysis Warhead - Follows a similar pattern with Crysis.

Crysis - This is the game I tested the most. During gameplay the GPUs rock @ 99% when looking at a highly detailed cliffside or at a close up forest. Whenever it seems their is loads of geometry to render, they rock hard and my FPS are 60-70 MINIMUM. However when I look off in the distance, it plummets to 40 or lower.

For instance, when you first land on the beach at night and the trek through the forest at night, my FPS were 70+ the entire way, but as soon as I hit the sunlight horizon......40. Another area later has me getting 60-70 running down this hill, but when I gaze off into the distance at an enemy camp, I get 40 (Usage goes from 95%+ to 50%).

Prophet comments on blowing up the gas station to make a distraction. Well when Im zoomed in on that gas station, Im getting 30 FPS or less with 40-50% GPU usage.

What I want to know, is why the hell are my GPUs limiting themselves and can I stop that. I don't understand that they limit themselves in Farcry 2 to 70% each and get me around 140 FPS. Why not limit it to 60 FPS and drop the usage to 30%? Does not compute....

8 answers Last reply
More about question crossfire setups
  1. Just out of interest what is the rest of your system?
  2. i5 2500k @ 4.2 Ghz
    Antec TP-750
    Asus P8P67 M Pro
    4 GB Corsair XMS3 1600
    128 GB CrucialSSD
    1 TB 7200 HDD
    HAF 922
    Thermaltake Frio
    2 x MSI Twin Frozr III 6950 2 GB

    Im sure you didn't need all that ;)
  3. Looks like we can eliminate CPU bottleneck. Enable v-sync then you are in sync with the refresh rate on the monitor for Farcry 2.
  4. Yeah, I will use Vsync whenever I need to.

    The issue isn't with Farcry 2 to be honest. Its with the GPU usage plummeting in the other games. I don't understand it.

    It seemed stable (yet only at 70%) in FarCry 2.
  5. Looking at your setup again I see that you have 4GB of ram. If you are running an 64bit OS it is possible that the game is reaching in your page file (HDD) which would explain the drop since HDD access times are a lot slower than ram access!
    You might benefit from a ram upgrade!
  6. I checked my task manager and it showed 71% usage playing Crysis.
  7. I just did a search here on Toms but did not find the article I was looking for but this instead, take a look at the conclusion,2778-6.html
  8. Im trying to set my minimum clock speed to the default 3d clock speeds of 850 and 1300 using ATI Tray Tools overclocking tab. However I keep getting BSOD. Its driving me nuts. I think this MIGHT help or fix the issue of the GPUs throttling down.

    Any ideas?
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