The 8500 and 9500 have two connectors. The 8100 only has one. I used my 8500 psu on my 8100 board when I was working on it as well. The same with the 840av. You need the connector from 840 psu though, the one that goes from logic board to psu. That is different that the 8100. Maybe the 8100 connector isn’t removable?? Post a picture of it