[RESOLVED, by TSD]1950x will not boot media comp.

Thanks, datonyb.

wardog, good grief!  I have said several times I have NO interest in W7.  How many times do I have to say I am sorry I even mentioned W7.  The SATA floopy (see the DL page for spelling) is for RAID use.  I have no RAID.  I also said I was not interested in chasing old problems. 
I have W10 x64 Professional installed on my TR.  All is well, I have no issues.  W10 installed without F6 floopy drivers.  All my special drivers are injected into the .wim files using DISM.  I have W10 x64 Pro installed.  I posted this in my first post:

Fatal1ty X399 Professional Gaming, Threadripper 1950X, 3xSamsung SSD 960 EVO, G.SKILL FlareX F4-2400CL16D-16GFXR, Windows 10 x64 Pro, Enermax Platimax 850, Enermax Liqtech TR4 CPU Cooler, Radeon RX580, BIOS 1.5

Thanks and enjoy, John.

ASRock TSD responded to my ticket and informs me that TR supports W10 RS1 and RS2.  RS1 requires disabling IOMMU in the BIOS.  I see no mention of this restriction in the ASRock site on the X399.  When first told, I did not even know what RS1 and RS2 were.  Here is a good reference:
https://en.wikipedia.org/wiki/Windows_10_version_history
RS1, Redstone 1, is W10.1607 and RS2 is W10.1703.  In my case the version of W10 I was installing was RS2, but I was using an older version of WinPE which obviously was not supported.  Building WinPE using the latest ADK (1703) solved my problem not the smaller size as I suspected.  I suspect this same restriction may be preventing the Server 2016 installing.  A wild guess is to try disabling IOMMU.  Here is am image sent me from an AMD document:

Enjoy, John.