MP 7,1 PCIe usb cards causing trouble with 2019 MP

[Gothboy1]

I have 3 Sonnet USB3PCIe cards Installed in my new 2019. They were previously in my 2008 MP and worked like a dream providing 12 extra USB ports. Now after install the 2019 won't fully boot just stalling on a black Apple screen. I’ve been able to use the card in the very bottom slot but not the ones located in the upper slots. Trying to plug in a USB cable to these cards crashes the computer. Is it the way I have them installed? Asking the experts here.

 

[Bigwaff]

Probably not compatible... how about telling us the brand and model of the PCIe USB cards, for starters? What version of macOS installed on the 2008 cMP where the cards were working?

 

[Gothboy1]

OWC Sonnet Allegro. El Kapitan. I was under the impression that the PCI3 cards work with the 2019 MP until the new machines come out requiring PCI 4 in 2026? Plus the one on the bottom IS working?

 

[reader50]

Presumably it's the Sonnet Allegro Pro USB 3.0 PCIe card. Click over to the Tech Specs tab, and it's specifically not compatible with the 2019 Mac Pro. No reason is given.

Sonnet has several other USB 3.x cards (usually 3.2 cards) which are compatible with the 2019 Mac Pro.