All done.
I have a stack of 12-14 year old MacPros running Ubuntu. They all have dual 4-core Xeon CPUs and most of them have at least 8GB of RAM.
Two are on my desk at work. About the only thing that fails are the drives, but they are easy to replace. A few of them had the graphics card fail. One of the techs here has a reflow toaster at home. He 'baked' the cards for me and 2 out of 3 came back to life.
The newest and the best is a 2010 5,1 we use as a PACS (Picture Archive and Communication System) server. SSD boot drive on a PCI card and 4 4TB server class drives in the bays in RAID 10. Everything else is the original parts. The thing is a tank.
I use the second one as a sand box.
I keep a third one on the floor next to my desk as a backup. Configured and ready to drop in if our either of our other servers go down.