オリジナル投稿者： Dan ,
Sounds like you have a cold solder joint on the South Bridge interface chip. Do you or a friend have the needed equipment to handle SMT components? If you do you could try re-floating it. This is a very advanced project and may fail. Otherwise, sorry to say I would try to get your money back, or look into getting a new logic board. Apple no longer services this model, but some authorized service centers still do (and may even have the needed parts in hand).