First of all, sorry for my bad English.

I bought my iMac in July 2011, Intel i5, 21.5 ", 2.5GHz, 8GB RAM, 500GB HD, HD 6750M and since November 2012 he stopped working. When trying to turn it back on 3 beeps sounded and did not turn on more.

After a few days, I turned it on normally, it was OK. On another day, the problem came back: while I was using it stopped working and did not turned on, just sounds of 3 on 3 beeps.

The screen does not turn on, goes black and no other sound is emitted beyond the beeps.

I've done testing of the RAMs, but nor replacing them it works.

Has anyone had this problem and managed to solve?