Let's talk riser cables. I keep encountering issues with riser connectors claiming to support PCIe 4.0, which seem to have sub-par performance. They work fine with the GPUs and NICs I tested them with, but attaching a nvme drive causes all kinds of issues and prevents the machine from booting. I guess nvme isn't as tolerant of elevated bit-error-rates.
That just doesn't inspire a lot of confidence in those risers, so now I'm contemplating mcio risers.
NVMe sits over PCIe. I'd be more inclined to believe they're playing games with their voltage levels to lower power consumption on mobile/embedded (not based on anything but I wouldn't be surprised). Or, if you're then going to an m.2 adapter, something with that.
That just doesn't inspire a lot of confidence in those risers, so now I'm contemplating mcio risers.