Express Switch Multiplier Expansion adapter

Hmm, interesting, thanks, and I see now there are PCIe expanders based on that idea. [1] I think the CM-4 + reference IO card + expander + PCIe versions of stuff I'd want are getting more expensive than makes sense (in comparison to say the ODROID-H2+ that has more built in and I'm finding hard to beat lately) but maybe someone will make a single IO board that's more appropriate for a NAS or NVR. This hackaday article [2] suggests the CM-4 would be good for that.

I looked up those bandwidth numbers:

    USB 2    =  480 Mbit/s
    PCIe 2.0 = 4000 Mbit/s
    USB 3    = 5000 Mbit/s

I keep looking for lower-cost machines for a fully-functional open-source NVR. I don't think I'd be likely to use more than 4000 Mbit/s between a couple SATA HDDs, a second Ethernet port, and a Coral or two. But the Coral can use more than 480 Mbit/s by itself. The USB accelerator product page [3] says "* Compatible with USB 2.0 but inferencing speed is slower."

[1] https://www.amazon.com/Express-Switch-Multiplier-Expansion-a...

[2] https://hackaday.com/2020/10/19/new-raspberry-pi-4-compute-m...

[3] https://coral.ai/products/accelerator