2012 Mac Pro and Catalina

At this writing, as long as Intel is not providing new microcode for these processors, the Mac Pro 2010-2012 are ending official support with Mojave.

A new variant on an old hack similar to meltdown has been discovered, and intel has announced they will not be fixing it.

see also this discussion nearby:

Mac Pro Desktop mid 2010 compatible with … - Apple Community

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Until Apple officially releases any information to the public around Catalina's compatibilities, we can only speculate what can and cannot work. You have the option to join the public beta and run Catalina on an external drive to see for yourself.

it looks like the 5,1s are will be dropped officially, but with DOSdude1 installers you can indeed run Catalina, but there are some asterisks, the base Airport chipset isn't supported, and looks like it won't be but the BCM94360CD or BCM943602CD chipsets, which can be upgraded on the mPCIe slot on the Mac Pros.

Keppler based NVidia cards appear to be erratic and buggy, (GeForce 680) and sidecar is blocked from running on any of the current Mac Pros (1,1-6,1).

So if you have a Metal compatible GPU + later wifi chipset (if you want to continue using wifi), it will run. Before someone chimes in about unsupported, there's a long history of users running DOSdude1 without hitches on older Macs and it's a stable way to bring a little more life out of your aging Mac as the performance of later gen OSes has not changed much.

@jlyons Looks like I triggered some sort of algorithm that flagged a previous post of mine.

Search: Definitive Mac Pro Upgrade Guide in Google, I tried to post links to various helpful sites. That'll help you out a lot.