Apologies in advance for this probably dumb question, I just want to make sure I understand correctly.
So I'm trying to install High Sierra on an Early 2009 MacPro (4,1) currently running El Capitan 10.11.6.
I've downloaded the High Sierra installer and patched it with the latest provided utility. I've then used the utility to transfer this to a freshly formatted (OS X Extended, Journaled) 32gb USB thumb drive, which worked fine.
However, whether I reboot and hold option down, or choose the USB thumbdrive as my startup disk in OS X, the only thing I get after rebooting and waiting a while is a black screen.
My GPU is a GeForce GTX 660 Ti.
Do I need to pop in an older GPU in order to make this work? Is there no way to do this headless?
Could I remove my startup HD from my tower, mount it externally on my laptop (already running High Sierra) and update it there?
Or any other possible process that DOESN'T involve switching out the damn GPU?
I ask because I bought this machine in 2009. I really have no idea where the original GPU even is now - that was several moves ago...
Thanks in advance for any ideas!