ok i now placed the ps3 near my window
it sucks the fresh air and blows the warm air into the room (free heating lawl)
its now extreme quite(i can only hear it when everythings quite and i stand next to it)
i can test it the whole day but no freeze(but mM still says 67°C xD)
well if that issue is appearing again ill do a reball
thanks guys
EDIT: happens again ... >.>