I don't know any other sure-fire way to test a motherboard or cpu other than to swap it out and see if the problem goes away. There are no user-level diagnostics for that. If you know anyone with a lot of PC building experience, they may have spare parts you can borrow. I'm not suggesting in any way that you need to spend money to troubleshoot but you have to realize there's only so much we can do in a forum environment. You're better aware of what resources are available to you than I.