Re: ATI Card Problem
The default open-source Radeon drivers are NOT going to help your overheating problem as they don't include that feature.
As to the AMD drivers, the latest 12.x version (it's either 12.2 or 12.3, don't remember which) claims to have improvements over the earlier versions.
Take a look at the download on the AMD Linux Driver page and see if the Linux version there is newer than the one you have.
If so, that could improve your situation.
Ubuntu 14.04, Mint 17; MS Win 8.1.
Will not respond to PM requests for support -- use the forums.