6770 Coil Whine

Hi everywhere, im from Argentina so, sorry for my English  

Today i bought a cooler for my 6770, i choose an Artic Cooling L2 Pro

After installing it, i decided to run a Heaven Benchmark 3.0, and i heard a strange noise ONLY when the GPU was on charge. At idle, there isn't any noise.

I decided to remove the L2 Pro cooler and put the stock cooler again. The same sound, witch is like the Coil Whine of the AMD 7900. I have never heard this sound, everything was working fine yesterday

Have anyone have an answer for this? Thank you very much and i am sorry for my English.