Had to upgrade from a 99% vanilla Yosemite install. My SSD was dying and finally decided to upgraded to High Sierra. Upgraded to (UEFI and Clover) from (MBR and Chimera.) Only issue I had was with USB which was fixed with Clover ACPI USB patches. There is a learning curve with Clover bootloader, but it works so much better than Chimera. CloverACL worked perfectly for audio. Only downside is my TimeMachine drive stopped working.