I'd like to learn to fix these myself, is there a good thread around here that covers most issues with these boards?
There is ZERO info as to what typically goes wrong. I too would give my eye-teeth to get a handle on it. The only general symptom usually is the Vcore regulator shutting down (red LED light on board near the PCIE sockets not lit). As to *why* -- unknown. Either the regulator itself fails or a chip or bypass cap shorts out shutting it down.