Highest 6950 Overclocks?

Hey guys, I recently put a Artic Cooler on my XFX 6950 because the stock cooling was total crap. I went from 90c under load to staying under 60c

So I have afterburner and was testing some clocks. I got as far as 1ghz and 1450 ram clock lastnight on 1.175volts   totally stable for a while anyway, but only tested about 10 min in Kombuster and BF3 Max temps hit was 62c at that clock!


I feel like I could have easily pushed it farther based on the temperatures but got scared and backed it off a bit for normal use...

So Im wondering is heat the main factor when OC'ing or is it best to just not run paast a certain point even if its low voltage stable? Ive heard of guys struggling to get past like 900/1350 and I have ZERO issues running cool at 1ghz/1450ram is that normal with aftermarket cooling? What are the high end clock thresholds??