macOS High Sierra 10.13.2+ 10 Gigabit Ethernet
Apple has been paying more attention to its Mac base. eGPU is the most welcome addition to macOS' feature list. There are also driver support for a few more performance components in High Sierra. I briefly covered NVMe flash storage support in this post. I found out recently adding an affordable 10G NIC is a possibility as well.
10.13.2 has native drivers for Aquantia AQC107 to support the iMac Pro. There are PCIe cards with this same chip. One of those is the ASUS XG-C100C. My local Micro Center store has one in stock so I decided to try it out. Through a Thunderbolt enclosure, the NIC was detected immediately in High Sierra. D5aqoep on insanelymac noted that macOS 10.13.3 update made some changes to the card's firmware for better functionality in High Sierra.
I hooked the XG-C100C in an AKiTiO Thunder2 and connected to a MacBook Air. I ran the 10.3.3 combo update with the enclosure attached. Here are the screen captures of macOS detection of this 10G card (left is 10.13, right is 10.13.3)
Next was to try this NIC in the Mac Pro tower. With this card installed in the PCIe slot, the cMP would not POST because of PXE boot. Mikeboss on Macrumors suggested shorting out pin 4 & 5 to disable the boot ROM. I took the heatsink off the XG-C100C to identify the EEPROM and look up additional information. You can find this IC specs with part number MX25L3233F.
This was a late night project to test the theory so pardon my soldering job. I'm very glad to report shorting out the EEPROM allows the Mac Pro tower to boot with this 10G NIC. Everything is showing up correctly. There's no sleep issues. Here are some screen captures.
$99 for a 10 GbE card that works with a Mac is a lot more affordable than options in the past. The price of switches is still high though. Hopefully as more people adopt 10G Ethernet gear, we'll see more reasonable solutions.