For what it is worth, I snagged a 9pin male to external USB-A male cable off Amazon to try and close the legacy USB loop with these cards. I plugged in the USB header cable that came with the card into the USB header port on the card, and this cable into the other end. I drilled a hole in available space on a Sonnet USB3.1 card to get the header through and plugged into available USB ports on both my Sonnet card and the cMP. Regardless of which USB port it is plugged into, the TR recognizes legacy USB devices as USB3.1. Both TB3 ports on the TR recognize legacy USB devices. I've tested several USB sticks and SATA enclosure. Later I'm going to test a USB camera. Link to the cable on Amazon follows (Note: It actually ships from China so it will take a good while to get to the US):
Panghuhu88 9pin Male to External USB A Male PC Mainboard Internal Data Extension Cable
Features: New and high quality Computer motherboard Internal USB 9pin Male to External USB A Male data extension cable Material:24AWG Length: 20cm Connector A: 9pin male Connector B: USB A male Package include: 1 x 9pin to USB extension cablewww.amazon.com
Similarly to mangombia I've got the usb 2.0 header working in my 2009 Mac Pro 5,1 but internally; no drilling. I have my Titan Ridge 2.0 card in slot four and an Inateck KT5001 in slot 3. I purchased a female to male USB 3.0 to 2.0 cable and patched it in. Had bluetooth interference problems immediately because the run was too long with the included cable. I subsequently removed the male pins and cut off the ends to make them female. devices which need USB 2.0 fallback now work in the port, old iPhones/iPads for example.
Inateck KT5001 PCI-E to USB 3.0 5-Port PCI Express Card and 15-Pin Power Connector, Red
Due to frequently updated drivers, please download the latest version on our official website to enhance your using experience. Features -Extend with 5 USB 3.0 downstream ports and 1 USB3.0 20-pin Connector (can expand another two USB 3.0 ports) for standard desktop PC -Support UASP:70% Faster th...
www.amazon.ca
axGear USB 3.0 to USB 2.0 Female to Male F-M Motherboard 20 Pin to Case 9 Pin Converter Cable
axGear USB 3.0 to USB 2.0 Female to Male F-M Motherboard 20 Pin to Case 9 Pin Converter Cable
www.amazon.ca
What I am struggling with, is getting both thunderbolt ports to actually provide power; note I actually have the card powered using both 6pin. The second works as a USB.. 2.0-3.1. First flash version (DSM2) right worked, second flash (GC-Titan-Ridge-V2.0-Mod-NVM50-CaseySJ.bin) neither, third (DESIGNARE-Z390-NVM33-Elias64Fr.bin) left works.
Running DSM SSDT, tried customizing with https://hackindrom.zapto.org; honestly I'm stumped. Any help direction wise would be appreciated.