I tend to do silly stuff with my Mac Pros. This time, I jammed an Intel Sparkle OC ROC A770 into my Mac Pro 2019. It worked well enough in Windows until it caused issues with macOS. The video contains the entire adventure.


As expected, the Arc A770 wouldn't work in macOS - the system recognized it only as a generic display adapter with no ability to output even unaccelerated video. This isn't surprising since Apple hasn't allowed third-party GPU drivers since macOS 10.13.

The card performed reasonably well in Windows 10, though benchmarks showed it lagging about 70% behind my Radeon 6900 XT. That performance gap makes sense given the price difference, but the Arc does have some impressive encoding capabilities that make it interesting for certain workflows.

Things went south when the A770 would enter full leaf blower mode whenever Windows went to sleep. Even worse, after my Windows testing, the Mac wouldn't boot into macOS at all. I don't know if the Intel Arc drivers somehow corrupted my EFI partitions, but when iBoot attempted to load, it failed completely.

Another thing learned from this experiment is that out of the box, the Mac Pro 2019 does not support Rebar (Resizable bar). Resizable BAR (Base Address Register) is a PCIe feature that enhances how CPUs access GPU memory by allowing them to view the entire GPU VRAM at once instead of in limited 256MB chunks. This technology enables faster data transfers between the CPU and GPU, potentially improving gaming and graphics performance, especially in memory-intensive tasks. AMD markets their implementation as Smart Access Memory (SAM) while Intel and NVIDIA simply call it Resizable BAR, but all function similarly by removing memory addressing limitations in the PCIe interface. There might be ways to enable it, but that's a battle for another day.