go with the Z68 Fatal1ty:
1| you're going to run sli which are dual slot coolers...i think 2.5 slots wide so you won't have heating issues when you'll have two of them 560's side by side
2| the maximus gene-z is okay but you'll later understand that the slots are really close to eachother. I've been checking out these two forum threads;
I would like to have the motherboad red/black as well to suit my PC.
Could someone give me info on 8x 8 vs 16x 16x?
no real difference,the 16x/16x may give you a couple more frames per second at low resolutions, but as the resolution gets higher the lower the difference becomes. It will become more important only when cards double in speed, which will be a while.