you have to crack open the case, find out what mm fan its is and if its a 3 or 4 pin. But who knows, HP might have some wack ass non-standard fan up in there for all i know? Fans always a standard thing, they go by size (in mm Dia.) and if its a 3 or for pin plug. check that. also, where is the fan? If its a CPU heatsink fan that might be tricky, but probably not.