I've used many dedicated GPUs on an almost daily basis for over 20 years. Mostly for graphics, but sometimes for GPGPU, crypto mining, and ML training. My poi

I've used many dedicated GPUs on an almost daily basis for over 20 years. Mostly for graphics, but sometimes for GPGPU, crypto mining, and ML training. My point is: Apple doesn't want to support external GPUs, because they've moved to a new architecture with the components of the PC integrated on the SoC, not across an off-chip PCIe bus. They've done that because the on-chip GPU has performance advantages on multiple dimensions. I've no doubt that Apple would love to retain those customers who want 1.5TB of RAM, and 6 GPUs churning away at whatever task, but ... it's not worth building a SoC to support that niche, and it's not worth the performance compromise that an off-chip solution would imply. The solution they've implemented in the Mac Pro, using PCIe switches to multiplex a bunch of slots across a handful of lanes, is treating PCIe as a secondary, low-performance I/O bus for things that don't need low-latency/high-bandwidth access to core CPU, GPU, and RAM. Which is fine for some stuff, but not really what you need for a GPU. I'm personally no fan of losing the expansion card model, but the tradeoff is worth it for most of their customers.