Hey TBird, your problem sounds a lot like one I had with a build of mine. I did everything you did, replaced everything you described and the last thing I replaced was the Processor. That turned out to be the problem. I was running an ECS Board with an Athon 1.33 GHZ. When trying to install windows I was getting errors and when I finally did get it installed it was doing the random reboots that you describe. This probably isn't what you wanted to hear but hopefully it helps you out.