Okay, how about this: The PCI slot goes on the bottom of the mini-ITX motherboard, and extends out of the bottom of the case. The GPU is in its own enclosure,

Okay, how about this: The PCI slot goes on the bottom of the mini-ITX motherboard, and extends out of the bottom of the case. The GPU is in its own enclosure, with a PCI edge connector on the top, and you stack one on top of the other. I'd really like to find a way to daisy-chain them, but I know that's not how multi-gigabit interfaces work. Raspberry Pi hats are cool. Why not big mini ITX hats? Yes, I just want to go back to the time of the Famicom Disk System, the Sega CD or the Satellaview.