ok. it really isn't desirable to have percisionX to use as a work around to keep the gpu from dipping down in usage. we didn't look at if your core speed was downclocking . .that could be heat related; not saying it is overheating
; my 550ti gets flonky when the temp hit 70c when it shouldn't have a problem and wants to downclock so i use the fan curve to keep the temps @ 60c.
you may want to run default clocks and use the fan curve to adjust the fan speed. if that works . .well sorta disappointing to have to use software to make a high end graphics card run properly . .oh, that a driver!