I'm running 9 x AMD 7970 split across 5 motherboards. Ordering my 10th tomorrow.
Highly inefficient. That should be 2-3 motherboards instead of 5.
The 5 motherboards form my base structure, I can now simply expand by adding further 7970's, I was aiming for three cards per motherboard. Got my riser cables now and cooling is under control!
Cfx.