I have the same evga board, and I know what u mean with the heatsink. You should install the heatsink before u install the motherboard, as its a little easier. I just put mine together today and games run fine with the 8800gtx. I had to kinda jam the pins of the connectors into the motherboard, I just prayed I didn't break anything. Before you install it make sure the posts are twisted in the right direction and then press down equally, holding all sides stable untill they click, then twist to secure it.