Okay, I upgraded my processor to the Athlon x2 5200+ from the 3800+. With the 3800, the PC boots up fine with 3GB RAM, but the 5200+ won't. At first I thought it was a PSU problem as I had a 500W SLI PSU, but received my new 700W SLI PSU today. I put the new PSU in and turned the PC up with only the 2GB in and it ran fine, then turned it off and put the extra 1GB in, and now it won't boot, it just hangs at a black screen after POST with a white cursor flashing. All I can think of now is it being a motherboard problem, but I've also been told about some memory remapping, but I thought that was only with older processors. Could anyone shine some light on this?