Hello, I have recently bought a new i7 27" imac and when the imac goes to slep it seems to crackle/buzz very very faintly. I phoned apple who told me to do the following: Turn off the imac. Hold down ALT, CMD, and R, and then hold the power button. Then still holding ALT, CMD, and R press the P key. Can anyone tell me if this is likely to do anything and what it actually does? Will it mess anything else up? Thanks.