UPDATE: I have been benching PCMark05 with my GPU @ 2x instead of 16x for past 4 chips. Hopefully that makes a pretty good difference.
DFI and there 2x "16x" slots where 1 is 16x when solo, but the other is 2x when solo and when in SLI both only 8x. I don't like using the top slot it makes everything too crowded. Oh well I got it straightened out and the chipset block is mounted even better now.