Microstuttering is a giant multi-GPU problem and is why I had felt the games were smoother when I went "down" from a SLI rig to a single 4870 a year ago, even though the FPS of my SLI rig was faster. Unfortunately this big, big issue gets often overlooked. It's completely unrealistic to compare AFR frame rates with normal frame rates.
I was yet to see a microstuttering analysis for HD5970 but some guys at Donanimhaber (cenova and Source) did tests with a good selection of games: Crysis, Crysis Warhead, Batman:AA, MW2, GTA4, Dirt 2, Unigine Heaven, World in Conflict, Wolfenstein 2.
http://forum.donanimhaber.com/m_3702..._/key_//tm.htm
Out of these popular titles, the only game that wasn't reasonably affected by MS is Wolfenstein 2. All others are significantly affected.
In the graphs the X axis is the frame rendered and the Y axis is the amount of time in milliseconds that it took to render the frame at that exact time.
Crysis@1920 (1680 doesn't display much MS, weirdly)
Here you can see that FPS varies wildly between 40 and 75. Most probably, in these instances FRAPS showed FPS around 62, whereas it was 40 fps-smooth at that time. This is why you can't trust AFR's FPS.
Batman:AA@1920
MS kills this game even more, with FPS varying between 40 and 100(!).
MW2@1680 (1920 shows less MS in this game)
There is terrible MS half of the time, varying between 40 and 200. Don't forget that if momentary FPS goes 10-150-10-150-10-150 the smoothness won't be the average of that FPS. It will be the minimum. You will see 10ish FPS smoothness.
Dirt 2@1920 (In 1680 there is little MS.)
WTF. This could be the definition of MS.
GTA4@1920
Unigine@1920
And you thought it couldn't get worse than Dirt2.
BOTTOM LINE: Never compare dual GPU FPS to single gpu FPS. Back when I had a G92 SLI system I had concluded that the second GPU, while multiplying FPS by about 1.5-1.6, didn't contribute anything to the smoothness.
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