VTT= How do you know you need more VTT? freezes? BSoDs? 1.30 (1.33 real) is what I have needed so far. dont know if I should increase this (Im almost on border line=1.36)

I tried stuffing around with some settings to fix that video corruption error i was getting and remembered that i had changed this value yesterday. I had it at 1.4 and decreased it to 1.3 after reading somewhere that it was too high. It was after that i started to recieve errors. So i raised it back to 1.36 today and video problems have gone. Hope this may help others having similar problems.