Chosen Solution
‘‘‘Everything happened after High Sierra firmware update in my three Mac Pros :( Basically flashed Mac Pro 4,1 to 5,1 which had to be genuine Apple flashed to install High Sierra with flashed EFI Radeon 6870 to see boot logo. All My Radeons were display EFI Apple logo - now they don’t :( How to restore boot logo? :(’’’
I was afraid of this. I did the flash last year when Apple didn’t support it: EFI and Firmware update from 4,1 to 5,1 for Sierra Upgrade Solved I tried booting mine up off an external drive with High Sierra installed and got that EFI boot notification. I was afraid to do it on mine as I was already at 5,1. Now that Apple has put this in the High Sierra they are obligated to assist you for free with any problems with it. I would call them up and get a senior advisor on this fast. 1-800-MYAPPLE UPDATE Bart, please let us know what you find out from Apple as a lot of others will need to do this upgrade.
