Can you please tell me if you know why my GPU are throttling this way?

http://i.imgur.com/ocD5s8C.jpg I use 3x7990 on a asrock oc formula mb with 2 PSU delta IBM 1200w and corsair 850w connected.So power is out of discution.Tried any type of overcloack or default.

The problem is that i get 47 CPD when they are throttling very fast like in this printscreen and when they are "lazy" get 40 CPD.