Yes, I meant the after you open the case, turn it on and when it starts to buzz blow cool air toward the fan on the Video card.This is only to verity that heat is making the fan twist a little and it starts to rattle.
There is only 12 volts inside the case. But don't be touching things while it is running. You might stick you finger into one of the fans.
I just assumed your Graphics card has a fan. Is that right?
The fix is to loosen the crews a bit and snug then up again. This should relieve the stress on the frame of the fan.Not too tight please.
Maybe is is something else and not the fan. But I can not imagine what else could do it.