djtimyd
macrumors newbie
You can boot to recovery partition with just a normal RX580, not need flashed card or original Apple card.
In some case, disconnect all monitor but only leave one attached will help (if screens stay black after boot to recover).
I have never heard of this, my understanding was that if you have a non-apple flashed GPU, nothing is available until the drivers load, which is right before the login screen - perhaps I'll try it at some point...
Also, Original Apple card can also boot Mojave, and the associated recovery partition. So, you won't lose any ability to do that.
AFAIK, this is wrong. Mohave requires Metal support, and the original card in this machine (5770) does not have Metal support. I know THIS for a fact as I was unable to run the firmware update that is the first part of the Mojave install because it would fail due to a non-metal supported GPU.
Regardless, its irrelevant to the issue at hand, which is now resolved.