If its two months after then its no longer your responsiblity as anything could have been done to the card. Tbh if i have solde some a electronic item on ebay unless they dispute it straight away, as in they received the item broken or that sort of thing, after that period i straight off dont believe people because they could have done anything to the product that i dont know about? especially if its a graphics card cause the person could have messed up a watercooling setup or volt modded the card or somthing along those lines.