7 beeps on startup with fans but no display

Hi,

I was given a Dell laptop the other day with gave out one monotonous beep every 3 seconds. I managed to reflow some of the ICs on the board and it now gives me 7 beeps when I power it on which I think suggests something to do with a CPU cache error? I contacted dell but they would't tell me anything about how to fix it and instead offered to repair it at cost. Typical! I have tried reflowing the South/north bridge and CPU which provided no result so I would be grateful if anybody has any suggestions.

Thanks