Hello,
today I was configuring CF under Win 10 x64 and discovered the following setting in newer NVidia drivers:
(as I later found out, it was introduced since driver version 368.22)
I tried this option and was very impressed - it gives almost zero mouse latency in game, far better than Adaptive V-Sync I used before.
However, when Fast Sync is selected, Crossfire crashes within 10-30 seconds after launch and the launcher says "[x]:Crossfire Crash Exit - CODE ffffffffc0000005 [E000000D3]".
I wonder if somebody else could try this setting with CF and see if it works.
P.S. Looks like Fast Sync support was added only for Maxwell and Pascal cards (Geforce GTX 750/750 Ti, 800M, 900 and 1000 series, Quadro M series).