The problem comes when the processor reaches a temperature of 60 degrees. the processor frequency go down to 1397 MHz from 4520 MHz. also with the normal frequency of 3500 Mhz I have the same problem.
I have tried disabling the cool n quiet but this did not help.
my specifications are:
Motherboard: Asrock 970 Pro3 R2.0
Os: 64 bit win 8.1
Processor: AMD FX-8320