Need advice - I bought myself windows 8.1 after trying it a few weeks back and getting a significant min frame boost with DX. I waited till I tried mantle before I bought as I thought I would get the boost for free, but for me mantle works for about a minutes gameplay and it then starts to drop frames badly. Now on 8.1 my gameplay is very stuttety, especially if I engage v_sync. I spent hours last night trying everything, disabled upls, hyper threading, UN parked cores, back to 13.12, and even did another windows clean install with a new install bf4 again. I can't think of anything else I can try, the only odd point is, in settings for bf4 I no longer have an option for 60 Hz, only 59.94 @ 1080p. Can some please advice.