Now i really wish id bought the Mac Pro whilst it was still available in the UK, instead i (stupidly) held out for the refresh, so instead of having to do some slight hacking of a couple of GPU cards, ive now got to build and hack together a hackintosh PC that can output Thunderbolt, so i can hide it away from my desk and use my iMac as a monitor.
I tried this with a Gigabyte Ivy Bridge Thunderbolt mobo. No go. OSX is using some SW to verify it's a Mac on the other end. It has to be a Mac or it won't work. At least that's my experience. Granted I was running Windows, my 2011 iMac refused to show anything but a Pci to Pci bridge.
Sorry to thread hijack. As you were...