400w's is good but you are demanding alot from it, as you well know oc'ing is affected by the psu, RAM and temp, Have you torture tested with prime95? We'll be able to tell more from that... make a note of the temp, i suggest leaving it on for a couple of hours to be on the safe side. not sure about the ratio but if your running an intel i'm not sure whether you have access to it, well i dont think i do - lol, but i'm still learning myself. sorry that i cant be any more of a help. Jag