I've read the tutorial on this site for troubleshooting this, and nothing has worked. I can't even get to the boot menu, I'm getting all fans except rear case fan turning on and everything looking normal for 3-4 seconds, then it stops. restarts again, and this time i get a mouse pointer and flashing "_" in middle of screen, and also my rear case fan working, but then it dies again, and this loops into infinity. I've fully reassembled my computer and tried all RAM fixes. I suspect it is the motherboard at fault, due to the rear case fan not functioning.