Installed BIOS MKQ7710H.86A (version 0071) and booted into flash drive installer (Debian-based.) Installer finds Samsung SM951 NVMe drive on PCIe riser card and installs. BIOS set to UEFI with legacy disabled per p.20 of http://www.intel.com/content/dam/support/us/en/documents/ssdc/hpssd/sb/nvme_boot_guide_332098001us.p... this guide. On restart, BIOS detects no bootable drives and halts.
NVMe was just a twinkle in someone's eye when the BIOS for the various 7 Series boards were produced. The short answer is that the ability to boot from the drive will only exist if the NVMe drive includes an Option ROM (usually a flash IC) that provides a BIOS extension (UEFI and/or Legacy) which supports the drive being identified and read by the BIOS boot loader...
I'm not intimate with the process, but somehow I thought UEFI was capable of some kind of handoff that would enable the drive's boot image to be found.
Assuming that's not the case, we will probably have to add a small mPCI or SATA boot drive.
Sadly, there is a lot of misinformation out there [There's even a motherboard vendor who claims that UEFI = Graphical BIOS Setup and that, because they were the first to offer Graphical BIOS Setup, they were the first to have UEFI. What a joke; the two have nothing to do with each other. Intel's desktop boards, for example, supported UEFI for almost 5 years before Graphical BIOS Setup ever appeared. You don't need UEFI to have Graphical BIOS Setup either; legacy-only BIOSs can also have Graphical BIOS Setup (they just rarely do)]. I rant. Anyway, you should think of UEFI as providing a building block approach to building a BIOS. UEFI has many capabilities that legacy BIOSs didn't have, but this is not because legacy BIOSs couldn't have them; it is because (a) UEFI is newer and people tend to develop new things on newer platforms and (b) UEFI provides a better framework (pun intended) for developing such features.
To understand this issue better, take a look at this (PC World) article: http://www.pcworld.com/article/2899351/everything-you-need-to-know-about-nvme.html Everything you need to know about NVMe, the insanely fast future for SSDs. It's a dated article but it does the job...