This card currently works with High Sierra pending a move to Mojave on my mid 2010 Mac Pro 2 processor. Some problems with sleep, i usually have to reboot in the morning, but otherwise works OK so far. Be careful if you reset PRAM - you will get no screen unless you also unplug and replug your monitor. It put me to work for hours until I discovered this. Boot up of course is blank and after talking to XFX I don't think there is a way to flash, even though it is technically AMD. Two power cables from logic board can be gotten from Amazon -- COMeap Dual Mini 6 Pin to 8 Pin PCI Express Video Card Power Adapter Cable for Mac Pro Tower/Power Mac G5 15-inch(38cm