I just tried updating my Mac Pro 5,1 to El Capitan. I am using an non-EFI GTX 980 Ti. I've installed several VNC apps to make sure I can control the computer virtually once the installation is done. This has normally worked in the past. When the installation begun the computer said it would restart. Instead, it hung. I ended up doing a hard shut down and then booted it up again. Now the fans periodically go on and off and it restarts itself on occasion. Is there anything I can do? I am thinking about going to the store tomorrow and buying a hard drive enclosure, taking the SSD out of the Mac Pro, and using my nMP...attempt booting from my 5,1 SDD on that computer. Does anyone think that would work?