I plan to add 2more gb of ram for my computer but pny has seemed to have stopped selling the ram I already have. I have 2gb(1x2gbsticks) of pc2 8500. I was wondering since I am not even running the ram to full speed (I am running it at 333mghz) could I just buy 2 gb of another company pc2 6400 ram? will I have any compatibility issues?