On: Double Standards

[lawlessone]

Can I stick a 4090 to it?

I know it's a terrible idea, and I can't afford the mortgage, but can I?

[geerlingguy → lawlessone]

I certainly will try it, once we get AMD drivers to a happier place. Unfortunately, Nvidia's proprietary drivers are not ideal for community debugging, and Nouveau is a little rough on arm64.

[mikepavone → lawlessone]

The current answer is maybe: https://github.com/geerlingguy/raspberry-pi-pcie-devices/iss...

The PCIe implementation on the 5 is supposedly more complete/less broken than on the CM4, but so far the only person crazy/inspired enough to test hasn't gotten back to this card with their Pi 5 setup.

[rahkiin → lawlessone]

No: The RPi5 has 4x lanes, the 4090 requires 16x lanes of PCI3.0

[0x457 → rahkiin]

No, it doesn't require it. It's desired to fully utilized it, but not required.

PCIe is fully backward and forward compatible between versions. Many eGPUs run at PCIE 3.0 4x.

[ssl-3 → rahkiin]

Does it require 16x?

Previous-gen video cards were often connected to risers that only provided 1x, and lots of "normal" systems (with a bit of expansion) don't have enough PCI Express lanes to give 16 lanes to any one device.

[Sohcahtoa82 → rahkiin]

> the 4090 requires 16x lanes of PCI3.0

Does it require 16x PCI-E 3 just to run? Or is that just a minimum to get the most performance?

[HankB99 → rahkiin]

RPi5 exposes 1 lane on the PCIe connector. It routes 4 lanes to the 2040 chip that provides much of the board's I/O.

IMO 1 lane is better than none. I love the CM4 because it exposes 1 PCIe lane and that can support a NVME SSD making it the first Pi that supports what I consider to be a decent storage interface.

[taspeotis → rahkiin]

No: it does not