Battlefield 3, Frame By Frame
Long frame times are most jarring to me when there's a lot of on-screen movement. While slowing down usually helps mask this phenomenon somewhat, that's not really a viable workaround in first-person shooters and racing games.
We've established that it's difficult to record evidence of this phenomenon in multi-card configurations. But Fraps does make this possible in single-GPU systems. We're using it today to record performance in Battlefield 3.
It's difficult to generalize, but many folks can tolerate a 20 FPS minimum. So, we set an upper limit of 50 ms per frame to assure reasonable fluidity. Beyond that, adding time per frame can be a much more intrusive distraction.
The sad fact is that even with an average of 50 FPS (shown on the previous page), our fastest memory configuration can't reliably keep the A10-5800K's on-board graphics processor under 50 ms per frame.
Of course, maximum rendering times get worse as resolution increases. Memory latency could be an issue, but even pricey low-latency kits are barely better than the DDR3-1600 CAS 7 config we tested, or this setup's DDR3-2133 CAS 9 arrangement.