81.0 C is very high IMO. So are your RPM's and especially your HW errors. I use 4 x 7950 and on every pool I'm set at 18,18,18,18 intensity. I can easily go to 19 or 20 but this starts causing the rejects to increase.  Besides, I figure the less strain the better. I have my max. temp set at 70C in CGMiner. My TC is 22,400. All cards are always around 68C and RPM's 1800 to absolute max 3000 without air condiitioning. When air condtioning is on its 1800 to 2400 RPM. I never see even 1 HW error. IMO you are going to burn out your cards quickly unless you get the cooling down. Do you have a big fan ?

EDIT: I have 8GB Ram and 6 core processor.