How the hell did you manage to overclock your card to 925 MHz? (Your default clock should be 782 MHz, right?)
Are you sure that this is stable and won't damage your card in the long run?

About temperatures: I have the HAF 932 Tower Case from Coolermaster, which is fitted with 3 big fans and 2 small fans.
Cool Air is getting sucked in and hot air will get out - so there is a good airflow already.
One of the big fans is right next to the GPU and blasting cool air in. No need for a extern fan.

@ trell0z: Okay, i will try it. But i think F16x16 is already the best option. I used autotune to get that value.

Did anyone of you guys try to change some driver settings?
I still want to know if there is an option to improve the performance for the mining task.