Check out the module utilization chart, either in the RK11-C Engineering Drawings, or here: http://gunkies.org/wiki/RK11_disk_controller (at the top of the section "RK11-C Board chart/count tables"). On a stock RK11-C, slots 1-8, rows C-D (the bottom two rows) are empty. In the "Double Buffer" variant, they are full of Flip Chips. (I'll be documenting the added Flip Chips in the Double-Buffered variant 'soon'.) Noel