Neither of the clock rates you gave are correct. That's a very power hungry CPU and some shops put them on 90ish Watt motherboards. Why? Don't know.
I recently purchased a skytech shadow gaming computer. when I turn it on it says this system does not support the cpu underclocking cpu for system stability
cpu is amd fx4350 I have 500w psu and 8 gig of ram no idea what the mother board is...it underclocks to 2.81 ghz when its supposed to be 3.8 any ideas

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic