This is all just a design exercise, but it’s a rather beautiful one. How do you put 4 GTX 295’s in a motherboard? How to do combine 9 motherboards into one big disk? How do you stack 6 disks and cool them all? How do you combine 10 stacks?
This isn’t a practical design for a variety of reasons. But it’s great fun to study.
His earlier version is more complex.
And this is not entirely theoretical. He actually homebuilt his own CPU cluster in an Ikea cabinet.
The best home-built GPU cluster I know is the impressive 110-GPU Atlas.