Core clock drops down on GTX 660 when rendering


i have been experimenting with over clocking GPU to get blender cycles to render faster.
this is awesome and the result are pretty good :slight_smile:
I am over clocking with MSI after burner.

The problem is - from time to time the core clock will drop down and get stuck on 524 MHz.
when that happens, the core speed will keep that value no matter what the graphic card is doing,
and i will have to reset my computer, or reset the driver…

my Temperature is around 60 when rendering - so no problem there…

thank you!