They said that it's either slot 1 or 2. There's little clack clips on the heatsink. I assume it's one of the long black things...Or just a huge heatsink on the side with no fan. (that is, if it's for real a slot proc.) Just squeeze the ends of the clips together w/ pliers and pull on the heatsink unti it slips over the end of the clip. If it doesn't have these clips, then I'm not really sure how it goes on. I don't have much experience w/ older processors.