upgrading a mac pro 2012 to mojave..
just wanted to share:
my 2012 mac pro did not have a metal compliant graphics card.
got a used one (Nvidia Geforce GT 640 1GB GDDR5) for $135.(*)
after putting it into the mac it needed to install some bios, did a reboot ~ 10 minutes
then starting mojave upgrade - it went by the book < 45 minutes
total upgrade time < 1 hour including opening the mac, replacing the old graphics card.
the graphics resolution is more than enough for a headless server
now on a supported platform for another 2 years (and its warm in the winter w >250W power usage)
Karl
(*) there are much cheaper offers on eBay ~ $20 but i wanted to make sure it works in the mac