Hey there.
Not sure where to start with this problem - it's rock steady and passed 9 hours of prime95 blend, plus several hours of OCCT small and large linpack while furmarking, however sometimes it won't wake up from monitor power down (like, once every 1-3 days) and "stutters" when loading some webpages (locks up, mouse won't move, recovers).
Any ideas where to start with this one? I'm stumped. Not a heat issue, that much I know.