Three step guide to hardware problem detecting:
0. Do all the easy stuff first, as suggested above. CMOS reset, BIOS flashing, memtest, remove any overclocks, etc. If you think that it is a hardware problem, try these steps:
1. Remove everything from the motherboard that you possibly can. This includes non-boot hard drives, video cards (only if you have integrated), DVD drives, and all but one stick of RAM. If you can, replace all cables with new ones. I've had several crashing problems associated with faulty SATA cables.
2. If you're still having the problem, then you're in trouble. It's probably your motherboard, but you should try different RAM and HDDs before you make assumptions. If you don't have the problem, slowly add hardware until you get the problem again.
3. Once you get the problem again, set aside that piece of "faulty" hardware and keep adding the rest of your hardware to make sure that nothing else is causing it. If you don't get the problem without the piece you set aside, add it back in to make sure that it is the thing causing the error.
It's a slow process but it's about as thorough as you can get without knowing your exact setup. The system clock issues and the early freezes make it seem like your motherboard is screwy in some way.