What brand do you have? I have The Asus DUii version, And overclocking was a breeze, but the temps were very unstable. Was driving me nuts that I was getting over 80 degrees Celsius on stock. In fact when runny furmark on stock, the temps never stabilized. So I assumed its somthing i am doing. Since the cards do run quite hot as it is, I figured i might not have enough cool air coming in. So I added 3 More fans one more exhaust and 2 More intakes. It helped stabalize The heat, but I was still getting 80c+ . Figured Not much more That i can do then, and left It at that The cards just run very hot. Found out That It was quite Normal to get the temps i was getting. A few Months later it started to destabilize again. Still stock settings, never bothered with OC with temps that high. found a thread somewhere that I can seam to find right now. Where a guy mentioned he got allot of RMA'ed units for overheating, and all he did was replaced the thermal paste. Seams the stock thermal paste that they used on those models was kinda cheap if you ask me. Although it was very risky in the fact that you can void the warranty if you change the thermal grease, I did It anyways. Opened It and found that the paste was extremely thick, and it was so cured that i had trouble cleaning it off the heatsink. Had To scrape it off till it was clean. Then I used Coolermasters X1 Extreme FUSION thermal paste. I carefully applied a very thin layer to the core, and then added a small drop in the center of the core afterwards so that when I tightened the unit up again it would spread out as it needed too. After that i just prayed i did Not just throw this card away, installed it switch it on. OMG!!!! 20c off-load max 65c load on stock on load never past 65c, I am so impressed the with massive change that I decided to try a bit of overclocking. I eventually got it to run stable with GPU Clock 1125Mhz could do 1200Mhz and be stable but not for very long periods. GPU Voltage @ 1300mV Memory Clock @ 5800Mhz on GPU Tweak or 1450Mhz on AMD Overdrive, you have to bump the power max 20% Furmark still goes past 90 On those settings, the most taxing games never past 85, TJ MAx on these cards is 110 In case you did not know that already. I did find that when in silent mode or power saving mode, that games tended to crash my system. I am not sure if anything I said here helps. Figured I share my experience anyways.