cMP 1,1 I think there is an nvidia in it.
cMP 3,1 with a GTX 680 flashed or mac, I just moved it with a only 43" 4K monitor,
I can't boot it now, I have to switch a cable or add a monitor, very irritating.
I use the 1,1 for the Epson printers and adobe.
I used the 3,1 with at home for adobe with a 23" IPS at home.
Now I moved it to the studio too.
I have faster Macbooks but I need the 32gb and 64gb ram + hardrives.
My external hard drive solutions just die faster and I have to put in the drives in the mac pro anyway.
Clients regulary lose files after 2 years or something.
My next investment will be a windows PC, sometimes people bring nMP to the studio.
I don't think of a hard switch, just buying less macs ... I or we use 6 macs in total.