[detaro]

That's PCIe bifurcation, and needs the BIOS to handle this correctly and not just define "those 4 lanes are one slot connected to one device".

[Teknoman117]

Every single Ryzen/threadripper/epyc board I’ve played with has supported bifurcation.

[wtallis]

I've encountered a Threadripper motherboard that lacked the firmware capabilities necessary to use a passive PCIe x16 to quad M.2 board.

I also haven't seen those quad-M.2 boards listing support for the mainstream Ryzen (AM4) platform, only the Threadripper and Intel HEDT platforms. Have you gotten an AM4 Ryzen system to split its x16 slot into 4x4?

[Teknoman117]

Yes, but now that I look it up it's apparently a feature restricted to X370 and X470 boards. Doesn't really make sense to me considering the PCIe comes off the CPU.

[vetinari]

TR4 boards that were released at TR launch day might miss the firmware support for PCIe bifurbication in the initial release. However, it was added in the later firmware releases.

[detaro]

Good to know, in the past it has been kind of random where motherboard manufacturers enabled it.