Hi Dam right
I had the same problem, and found it terribly annoying. Every time I was playing Half-Life 2 or Doom 3, the game would suddenly switch to XP notifying me that my gfx card was running too hot.
I found a solution, though. I downloaded a utility called Atitool (http://www.techpowerup.com/atitool/
), which is basically an overclocking utility for ATI cards. Since this card is so fast, it's not (yet) necessary to start overclocking it, I know, but the Atitool also allows you to regulate the fan speeds on your X850XT-PE (start the programme, go to Settings, then to fan control).
For some obscure reason, I found that the factory settings's fan speeds were ridiculously low. Below a temperature of 90 degrees Celcius, the fan would rotate at 5% (!!!) of its capacity. Only at 91 degrees the fans would be used properly, which explains why ATI's control center told you this was the max temp).
So, what I did was change the settings to my own liking (tick 'Override fan speeds' and choose 'Dynamic based on GPU temperature'), namely -and here's the list-
above 0° at 40%
above 45° at 45%
above 50° at 55%
above 55° at 65%
above 60° at 75%
above 65° at 85%
above 70° at 95%
above 75° at 100%
With these settings I played Doom 3 at Ultra Quality and 1600*1200 without exceeding temperatures between 75 and 80 degrees Celcius, and Half-Life 2 crancked up to the max without exceeding 75°, or Rome - Total War without exceeding 70°, all for several hours in a row. All these temperatures are obviously a lot better for your gfx card's health than the 90 to 100 degrees it heated up to at factory settings.
So, I'd say, play a bit with the Atitool utility, make sure you set the programme to load at Windows Startup ('Settings' - 'Startup'), and when ATI's control center prompts you again that the safe temperature is being exceeded at 65°, tick the option not to ever give you this message again. This last thing is important, because you will exceed 65° regularly but you won't burn your gpu anymore.
Oh yeah, one more thing: on Startup, check whether Atitool's settings haven't reset (this happens sometimes) and enjoy the sound of your gfx card's fan ;-)
Hope to have been of help,