I bought the z270x Ultra Gaming with the intention of building a system with a Thunderbolt port, since I couldn't find the UD5 for sale anymore, anywhere. At least the Ultra Gaming has a Thunderbolt Header/Connector on the board.
After a lot of fiddling, I got Thunderbolt working by installing an Asus Thunderboltex 3 card in PCIx slot 4. I would have used the Gigabyte Alpine Ridge for this, but it's not available anywhere. Using the Asus card allowed me to connect (and register) my new UA Apollo 8 audio interface under Mac OS. Yay! So far, everything seems to work. I get Audio I/O just fine, but have yet to do a load test with a lot of channels going, etc.
The header cable from the Asus Thunderbolt card to the mainboard is critical, though. This has been said in another thread, but without this being connected properly, Thunderbolt will not even show as a configuration option in the bios. The original cable that comes with the Asus card doesn't fit (it's also 5 pin, but the spacing between contacts is too wide. It's a connector just like the old CD-ROM-to-soundcard audio connectors from back in the day, but it needs to be narrower than that), so you have to make yourself a custom cable for it. In my case, I removed the actual cables/contacts from the plastic connector, and put some shrink tubing around the individual contacts and connected them to the pins of Thunderbolt header on the motherboard one by one. This was enough to get it recognized (after installing all updated chipset drivers etc. under Windows 10 Pro, as well as the Thunderbolt drivers for both, ASUS Thunderboltex 3 and Gigabyte Alpine Ridge on the Windows side first). However, the cable I made doesn't have good contact and sometimes Thunderbolt doesn't appear. I think the connectors/contacts themselves are too big and should be a bit smaller for the pins on the motherboard. I'm still trying to source the proper connector for a better fit (someone at an electronic store said that I'll need a .5 instead of a .1 connector... not sure). Any tips where I could find this? Does this type of connector have an official name? (Molex something?)
Also, I'm using the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter, and an Apple 2 meter Thunderbolt cable.
I figured I'd also try updating the OS to 10.13.3, that came out just before I was ready to try all of this, and applied the Multibeast patches after that. This all worked out fine, and I'm running 10.13.3 booting from the HD at this point, using Thunderbolt with UA Apollo 8 and all.
Hopefully this helps someone trying to do something similar.
The other connectors I do not need.
