The processor resets the frequency, what's the problem?

Question

AMD

There is an ASUS M2N68-AM plus motherboard, and it has a Phenom II x4 945 percent. The processor is overclocked from 3 to 3.4 GHz, but under load it starts to drop the frequency, although the temperature does not rise above 50, what could be the problem?

Answer 1

1) Cool'n'Quiet
2) Deliberately resetting the frequency by the BIOS due to a lack of power in the CPU power supply circuits on the motherboard.