I think this is unlikely. All of Apple Silicon is based on a unified memory architecture. GPUs and CPUs share the same, incredibly high-bandwidth memory. In fact, the GPUs CPUs in unified memory are all part of the same chip package.

Whereas All current PCI-E graphics cards include their memory on the card itself. Which means the CPU is having to copy data to, and from the external graphics card to do basic video operations.

In this interview on The Talk Show, John Ternus, vice president of Apple hardware, says he sees no way to incorporate external graphic cards into the Apple Silicon architecture (at 22:48)

https://youtu.be/DgLrBSQ6x7E

They could be made to work for non-graphics workloads, potentially.

This is of course nonsense because GPUs in Thunderbolt enclosures work fine.

The problem is more likely that the SoC does not have a sufficiently good PCI-E implementation much like the RPi and other ARM SoCs.

Do they? While eGPUs were a thing for Intel macs, I don’t know if any external GPUs they could be used for graphics with Apple silicon, even in a thunderbolt enclosure.

My guess is it would be possible to get Asahi Linux to interface with a card, but it would likely run into similar quirks that we hit on other Arm platforms (like AMD driver issues with cache coherence on Ampere).

IIRC the actual limitation was the M1 only allows mapping PCIE as Device-nGnRE and that precludes eGPU/video cards. Using Linux doesn’t change this behavior.

> mapping PCIE as Device-nGnRE

Disclaimer: completely unaware of what that means.

Does it preclude such a card working _at all_ or can it still be used e.g for e.g CUDA?

Would it be possible for e.g Nvidia to create a special batch of cards or design that would work for such cases? (priced through the roof given the small user base but that'd also be the kind of user base who would drop stupid amounts of money without batting an eye)

Considering nVidia has the Grace CPU and probably a significant investment in arm64 development, I'd say yes absolutely. If anyone could do it it's them. Of course theres probably a better chance of Atlantis rising from the sea.

I wonder how powering it would work? It would need a separate PSU.

Are there no mac compliant thunderbolt to pcie adapters available?

Yeah, there are a few from Sonnet and other Mac-oriented companies. I guess that's what Avid and Pro Tools users were using from 2013-2019.