Is it still stable, after reboots and a total power off?
Might be worth looking around for an updated firmware for the board. There was one site that I found really useful when sticking a custom firmware onto my ageing board which I needed to get a recent GPU upgrade working. I'll post the link if I can find the site again.

seems fine now. Firmware was all up to date. I guess it just really really needed the CMOS battery reset for some obscure computers reason. Next thing to try is overclocking a lot!