buzzing 9800GTX KO

[mactabilis1]

I have just got a 9800GTX KO by evga it seems to work ok but when i play some games i get a buzzing noise ,Its not the fan and its not that i have not put the correct power to it i have a 700watt psu and have the 2 PCIE CABLES in place.
On 1 game i decided to run it in windowed mode,Now when i click the window it makes a buzz as well.
I cant not work out what the hell is going on.

Any ideas guys??