The same people with a simliar larger heatsync fan with lower fan speeds (good performance/loudness for the price cooler) are getting 10-20C lower than me. Something doesn't add up. Even though I get prime95 errors after a few hours...i get no game crashes and the only way i can tell is that i alt tab out of wow and go check to see if all cores are still running. It also is random which core give an error and the speeds vary from 3.5 to 3.8 ghz with little difference in length of time it takes to cause the errors.
your temp propes might be correct because really, the temps of the chip gets affected from the surroundings aswell, and also that AC64 really just isnt a top performer. and in terms of stability, anywhere from 4hours+ are usually considerably stable in ppls own terms. I.e. some considers 4hours are stable for themselves, some does 6 some does 8hr+ stresses. but nonetheless; if you can stres 6-8hours then you're 99% rock solid. after 8hours is rock solid.
i believe the 810 atm is having a sale too.. its probably 20-25bucks more than the 720 i'd believe.
EMCLPNP29 for additional 10bucks off. =P