Netkas (netkas.org) spent years getting non-Apple GPUs and eGPUs working on Macs with varying levels of success. I flashed a PC Radeon to work on my Mac Pro 1,

Netkas (netkas.org) spent years getting non-Apple GPUs and eGPUs working on Macs with varying levels of success. I flashed a PC Radeon to work on my Mac Pro 1,1 with help from the Netkas forums sometime around 2010.