Chosen Solution

Need fast backup to External Thunderbolt storage drive. Does anyone know of a card or other way to do this? On either a 1st generation or 2nd generation Mac Pro. UPDATE 9/15/18 Looks like Sonnett makes them but I can’t tell if they work in Macs: https://www.sonnetstore.com/collections/

https://www.sonnetstore.com/collections/

Short answer: No. Longer answer: Thunderbolt is essentially PCIe on a wire which means that it HAS to be part of the motherboard, so what you’re asking for here is a way to install a PCIe interface via a PCIe interface. Can’t be done, at least not without the motherboard directly supporting it (which the Mac Pros do not).