[Henri Pigmans]

I think it is not due to you BM card but due to the fact that Premiere makes a temporary render in uncompressed full frame HD.
I noticed the same problem when I go to After effects with a clip add any effect and return to Premiere. The timeline will play un-edited clips flawless but when it arrives at the aftereffects clip it plays a couple of frames and then stops.
I have no solution yet maybe someone else does ?