Have you ever seen a mod where the video card(s) are outside the case by way of motherboard header extender? I thinking of a mod where the video cards would be water cooled but externally mounted. I'd love to see someone try this. From what I've read latency isn't much of an issue but power loss is.
Details I was able to google.
http://www.magma.com/products/pciexp...ox1/index.html
http://www.guru3d.com/news/asus-rog-...ard-announced/
http://www.youtube.com/watch?v=4FnHg-k8N3Y
http://en.wikipedia.org/wiki/Nvidia_Quadro_Plex
http://en.wikipedia.org/wiki/PCIE#External_PCI_Express