I decided it wasn't worth buying a real Mac Pro so I don't know which CPUs are still good today and which are showing their age.
Ya right. Apples is one of the worst companies when it comes to hardware updates. Even if they do release GPU upgrades you can be sure they'll cost a small fortune.
That’s assuming Apple haven’t gimped it to prevent you running it on 'their’ outdated equipment. I’m keepong a good eye on those Accelsior cards. If I see one in the sale it’s mine.