HD7850 desktop mode high gpu usage ?

Hi all,
i just joined up, i had been follow this forum for years but decied to register for ask my problem

and english is not my native language so i can make mistakes sometimes, excuses..

anyway i had purchased my sapphire 7850 2gb dual-x 2 days ago

everything was perfect, can play my games high settings

but i start to hear a sound from gpu at high frame rates

i searched and its coil whining

and today i have serious problem

game performance dropped, nfs most wanted yesterday 50-60 fps and today 19-20!!!!

no 3d app running but my gpu usage on desktop is %90+

here is a SS, i dont know to to add picture so i give the link of my screen
http://img202.imageshack.us/img202/2348/ekrangrnts10.pn...

using 12.11 beta 11

is it a software or hardware error

Thanks,
Doğan.