I'm thinking it could be the motherboard the guilty. because this is the second time we are changing the ram kit and third time changing the graphic card.
Dirty keyboard? The keys pressing onto the screen while it is closed, leaving a faint 'chessboard' like pattern.
Without a picture I'm really guessing, but I'll try guessing something that hasn't already been mentioned.
Dirty keyboard? The keys pressing onto the screen while it is closed, leaving a faint 'chessboard' like pattern.
just guessing