An authorized repair center said they changed the motherboard of my iMac 27" but I have doubts since I can still experience the problem for what I had it repaired.
I was told on a forum that if the computer's SN was invisible or started differently in the About this Mac menu it meant that the MB had been replaced. I'm seeing the same SN so it should mean that the MB was not replaced, but on the phone the repair guy said this method is wrong.
What do you say ?