There has been rumors going around on this issue.
I have read a statement in MaxiumPC(watch dog section), that there is no real issues with the drivers and the temp increase is within margin. And then I found this?
"ATI is aware of this problem and actively working on a fix. The workaround as has been documented on our tech support site
here is to use CATALYST 3.7 which does not exhibit the problem. We are fairly confident that the next CATALYST posting will fix the problem. Apologies to all gamers out there".
Just as Firing Squad reported here too I experienced same troubles while playing Call of Duty.
In this game, everything works perfectly on Sapphire Radeon 9800 Ultimate edition 256
MB DDR II even at the heaviest settings possible -- 1600x1200 FSAA 4X +8 Aniso -- until the military jeep chase.
Full story here.