So there seems to be a lot of discussion about exactly how many GPUs you can fit into one motherboard.  One of the posters on this thread got 8 with win 7 64 bit, MSI77A-G45.  However...as a noob, I note there are only 7 actual slots.  Even with risers how do you get 8 GPUs to fit in 7 slots?  Do you have to use at least 1 double GPU unit (e.g. 5970, 6990).

https://bitcointalk.org/index.php?topic=234090.0