installed MBM5. Dont see any heat issues. Not using the overclock facility that comes with the catalyst control center either cos the heat increases pretty quick when ya do.
AH is the only app I get any graphical issues in at all and, as I say, if I screw around with the settings I can get it to run perfectly ok for hours at a time. I just have to switch back and forth on vertex wossnaming to do so.
Havn't tried running AH on just the one core yet, will do so when I get a sec and let you know.
And as per email, I do have the AMD dual core fix installed.