you mean replace as in "get a new one"? Oh cripes. I reeeeally don't want to replace the motherboard. The CPU and memory have warranties on them, and they're not so hard to replace physically. the motherboard would be a giant pain.

Uhm. yeah. I guess I'm spoiled because my best friend owns a computer shop and every time I put a new pc together and something isn't right, I just take a new piece of hardware of the shelf to replace the possible culprit. This has been going on for so many years now, I sometimes forget other people don't have that option. Sorry.

I don't want to be pessimistic, but the last time I encountered such a problem it was a combination of memory and motherboard. Both were replaced.

Here's a tip : if you replace your memory, make sure you replace it with brand-on-brand memory. Much less chance of failiure on those.