Hi all,
I had a HD 6990, and was not getting the performance out of DCS A10 that I expected. After much research, I found out that DCS simply DOES NOT support crossfire. The issue is discussed here, where many people claimed insignificant gains with Xfire, or even worse: negative scaling. The issue was finally addressed by Eagle Dynamics here. Basically, its not supported, nothing we can do, and nothing they can do. When Nevada comes out, maybe it'll have better luck.
I was curious how the GTX 680 performed against the 6990 on DCS A10 but couldnt really find any comparisons. I felt confident it would perform better in this particular game, and while the 6990 benched better in most other games, I really only play DCS. I did my ebay research, and was able to get enough $ off the 6990 to switch to the new 680, so thats what I did.
In the process, I benchmarked the two to see just what the difference really is. The test setup is in my signature, but the actual bench consisted of the following:
Two 1-minute fraps benchmarks of a track specifically saved for this benchmark. I wanted an area with buildings, trees, and mountains in view. This was a setup I knew was hard on the 6990. All special settings on both cards were turned off, or to "application controlled".
Part1: Runway start at Senaki-Kolkhi with the TAD and TGP (white hot) on my MFCDs. I didnt pan the view, or move the aircraft at all. Just sat on the runway for one minute.
Part2: Right after part 1 ends, I throttle up and take off. 1 minute benchmark begins when the wheel brakes are released. Upon take off, the TGP is slewed to a point on the ground (in the trees).
I ran both benchmarks on low, medium, and high graphics settings on both cards. The 6990 was ran with cross fire on, and cross fire off (simulating a single 6970). BTW, the 6990 is on stock voltage, but overclocked to reference 6970 clock speeds.
here are the results, with specific settings and gpu usage as seen on MSI afterburner:
To put it simply, I was floored. Not only does the GTX 680 stomp my old 6990, but using crossfire actually reduced my frame rates! the 6990 performed worse than a single 6970 would!
This was an amazing and worthwhile upgrade in my opinion. The 680 literally doubles the framerates on high settings. Aoh, and the medium benchmark on the GTX 680, i forgot to turn tree distance down to 1500. It was run at 6000.
Clearly, your milage will vary. I'm not sure if SLI has the same issue as crossfire or not, so I can't really speak for anyone upgrading from a current NV setup. From the standpoint of anything AMD 6xx0 though, it's a definite improvement.
I plan to continue testing with higher settings, mirrors, and FXAA, so stay tuned for more info in the near future. Let me know if you have any questions or comments!