Micro Stuttering/jittering in frame rendering time

[Spooony]

See a lot of people having issues with it but no one can pin point the cause. have a look at this article
http://techreport.com/articles.x/21516

Wow. We've heard whispers from time to time about micro-stuttering problems with multi-GPU solutions, but here it is in captivity.
To be clear, what we're seeing here is quite likely an artifact of the way today's multi-GPU solutions work. Both AMD and Nvidia prefer a technique for divvying up the workload between two GPUs known as alternate frame rendering (AFR). As the name indicates, AFR involves assigning the first GPU in a team to render the even-numbered frames, while the second GPU handles the odd-numbered ones, so frames are produced by the two GPUs in an interleaved fashion. (AFR can also be employed with three or four GPUs, with one frame being assigned to each GPU in sequence.) SLI and CrossFire support other load-balancing methods, such as split-frame rendering, but those methods aren't favored, because they don't scale as well in terms of FPS averages.