Chosen Solution
I tried to put a AMD Radeon RX 5700 in my 2009 (flashed to 5,1) Mac Pro. I saw online that you can use one of the SATA ports for additional power for the GPU. My mac pro now wont power on. When I power on the Mac Pro, the DSI510 LED lights on the CPU tray, next to both CPU’s light up RED and it wont boot at all. Did I just blow my CPUs? Will buying new ones fix the issue? Help!
Put the old card back in and see if it runs correctly to help isolate the problem. Flashed cards are always iffy. What OS X are you running?
