MP 1,1-5,1 Wanting to upgrade Mac Pro Mid 2012

[mattspace]

The problem is really low level, USB1.0 and USB1.1 OHCI devices, what is called legacy USB, are 32bit only and require to have a very computationally expensive bounce buffer for 64bit usage - Apple started the OHCI chopping block back with Big Sur since no supported Macs are OHCI anymore and this will only get worse over time, it's EHCI/xHCI or bust now.

Since Mac Pro Intel USB controllers are OHCI for the USB1.0/1.1 speeds, this is a real issue for us, but not for modern hardware where the USB controllers are EHCI/xHCI native.

So, would a USB3 (or 2) PCI card also be a solution (assuming it would have a more modern controller on the card)?

 

[macguru9999]

So, would a USB3 (or 2) PCI card also be a solution (assuming it would have a more modern controller on the card)?

Yes, when my built-in ports stopped, the ones on my card kept working.

 

[tsialex]

So, would a USB3 (or 2) PCI card also be a solution (assuming it would have a more modern controller on the card)?

Yes, but be aware that is not for everything or every situation, for example, USB 3.0 cards only work after macOS loads the drivers and don't work with pre-boot configuration support at all.

The USB2.0/3.0 hub is a minor compromise and sometimes it's practically a requirement, like if you have a GC-TitanRidge.