@Perry It looks like your X10DAi doesn't support quad bifurcation. I can't find the exact documentation stating this, but I'm inferring this from the board not being validated for the AOC-SLG3-4E4R, which is a 4x4x4x4 bifurcation card. However your board is validated for the AOC-SLG3-2M2 which is a 4x4 PCIe x8 bifurcation card. In this case, try moving the M.2 drives to a different location on your Hyper M.2. You may get the drives to work in another port position.
Hmm. What's weird is that the BIOS definitely lets me set x4x4x4x4 bifurcation, and when I reboot and drop into the BIOS, its correctly seeing the two slots where the NVME cards are, and stating that they're each running at x4 speed.
I guess in this machine we could put in a dual NVME card and bigger drives, but that's a lot more expensive. We need a minimum of 4TB ultimately, because this has to cache tens of thousands of DPX image files, which can be as big as 100MB each.
When building our next machine, which I'd also do on a Supermicro, where should I look to be absolutely sure this will work?
As for Windows 10, it's potentially an option, but we're running some software on this that's pretty specialized and we are out of our support contract. So a Windows 10 upgrade will require a $2500 support contract renewal to get the latest version of the software. We're trying to avoid that.