AMD HD7870 Vsync problem
Enabling vsync in game FPS are limited correctly according to my monitor refresh (60hz) removing the tearing correctly, but the FPS intermediates are skipped directly from 60 to 30 and vice versa, I conclude therefore that the triple-buffering is not activated automatically.
So I did some testing, I created a specific profile in Catalyst trying Arma3 with any combination of vsync and triple buffering, but the game ignores any setting from the driver, and as we all know the triplebuffering in driver is specific for openGL not for DirectX. I also tried to force the triplebuffering with RadeonPro, but probably this program is not yet compatible and the game crashes at startup, in any case.
I am currently using the latest beta driver 13.8 beta2, but anything specific for Arma3 at the moment, so i don't think would be difference trying other versions, in other games I don't have this problem, even in BF3 which is dx11.