A developer successfully connected an RTX 5090 GPU to an M4 MacBook Air using a Thunderbolt eGPU setup. The main challenge stems from Apple Silicon's lack of native NVIDIA/AMD drivers in macOS, making external graphics difficult for gaming and AI workloads.

The tinygrad framework recently released macOS eGPU drivers, but performance benchmarks show they run about 10 times slower than native Metal inference on the M4 Pro. The workaround involves running Linux in a VM on macOS to pass through the GPU, leveraging Thunderbolt support in macOS and Linux's NVIDIA drivers.

Technical difficulties emerged with PCI passthrough, specifically when mapping device memory into the VM. The host kernel crashed when attempting direct memory mapping due to incorrect memory permissions. The solution required adjusting QEMU to use proper memory access flags, highlighting the complexity of enabling GPU passthrough on Apple Silicon hardware.