I'm guessing one of the following are the cause:
-The little sticky heat pads on the RAM have reached the end of their rope.
(Penny method works great for this)
-The X-Clamps are beginning to warp your mother board. Usually this happens when the xbox overheats. Not to mention the clamps are gripping the board WAY to tight anyways... (This problem is also fixable with some mechanical screws and washers)
-The crappy soder connection that comes in xbox's is beginning to give out and you will need your motherboard/northbridge/gpu reflowed. (Can do this yourself with a heat gun)
I know all of these methods work for a fact because I have used ALL OF THEM in my xbox360. It still works and since I reflowed it last time I have yet to have any promblems so far. Been running great for 6+ months now
