2 x powercolor HD 6850 cards performing poorly

Hi,

I spend about a grand for a computer to run parallel computations, but am not getting the performance that I expected.


Here is my setup:
- Intel Core i5 2000k
- MSi P67A-G43 (B3) Motherboard
- 2 x Powercolor Radeon HD 6850 775MHZ 1GB video cards
- WD Caviar Black 750GB hardrive
- G.SKILL Ripjaws 8GB Memory (2x4GB)
- All with liquid cooling for cpu and about 6 fans...

yes...i went a little tooo far and shouldn't be complaining, but its being used for mathematical computations through the video card.

So the benchmark of the two graphics cards using crossfire is 3315 from PerformanceTest. According to its website, videocardbenchmarks.net, a single 6850 benchmark is around 2800.

--> since they are running in crossfire, shouldn't the benchmark be higher, say > 4500? According to some websites, crossfire should double the performance.

Also..The home page of the radeon 6850 video card claimed it could handle 1.5TFLOP for single precision calculations. I'm only getting about 500GFLOP per video card, for a total of 1.014TFLOP.

This may not sound like that much of a difference, but currently my config is performing at 33% of what it should be.

Any ideas what the problem is? Could the motherboard be limiting the TFLOP performance?

Thanks!

shahster88 said:

So the benchmark of the two graphics cards using crossfire is 3315 from PerformanceTest. According to its website, videocardbenchmarks.net, a single 6850 benchmark is around 2800.

--> since they are running in crossfire, shouldn't the benchmark be higher, say > 4500? According to some websites, crossfire should double the performance.

Click to expand...

Try something like 3dmark instead.

Crossfire only works in fullscreen I believe. Make sure you are in full screen for both cards to work to their fullest.