This sounds very interesting! Since PCI-E and Thunderbolt are both two-directional communications, this should be possible. I think the transmitting and receiving pairs need to be swapped so that the the ASUS card and a graphic card can talk to each other. And then, I come up with some questions. What would provide the clock? If no one is providing, do i need an external clock? If so, what frequency? (I found 2.5GHz for PCIE 1.0, is that the same for 2.x?) What about the SMBus and JTAG in the PCIE pinout? What should I deal with them? May also swap the Tx / Rx of JTAG? What about SMBus?