Stumped - X370 SLI Killer/AC and dual SSD - Fixed

So here are the system spec's, I have even de-clocked my system from it's normally stable configuration and reset the bios in an effort to troubleshoot this thing.

ASRock x370 SLI Killer/AC
Water-cooled R7 1700 - Stock clock at the moment but usually 3.95-3.975 GHz
16 GB G.Skill Trident Z 3600MT/s RAM clocked usually at 3200 MT/s with 13-14-14-14-28-40-1T (currently 2933)
Samsung 960EVO NVMe 512 GB boot drive in Ultra M.2 slot
Adata XPG SX7000 NVMe 512 GB drive in M.2 slot
5 TB Toshiba X300 on SATA port
24x DVD-RW on SATA port
Water-cooled twin 1080ti FE card in SLI
1200w PSU

So here is the story.  I installed the 512GB SX7000 and then the 5TB Toshiba drive without any drama.  Everything was working great (data was consistent with the expected 1800 MB/s reads and 800 MB/s writes the SX7000 was rated for).  Then while at work, windows rebooted and my SX7000 drive disappeared as if it had gone bad.  Reseating it resulted in the bios looping over and over without booting and the bios reporting 48 GB of RAM as opposed to the 16 installed and the bios reporting the NVMe drive as 1TB and no longer 512GB.  Now like most people, I was assuming that I probably received a defective unit, however I ordered a PCI-e card for testing purposes and installed it in a 4x PCI-e slot.   Performance was significantly degraded (300-400 MB/s R/W transfer rates) but it was reliable and worked well - no data was lost.  Re-installing the card in the second M.2 slot on the motherboard once again resulted in the system refusing to boot or if it did boot, the bios was refusing to recognized the drive.  The Toshiba 5TB SATA drive and the Samsung 960EVO m.2 Ultra book drive were unaffected and performance remained unaffected as well.

So my question is:  What the hell happened that the second M.2 slot will no longer correctly recognize the drive in the M.2 slot when it was installed and running for nearly 24 hours without issue.  I have reset the MB bios completely and the problem persists.  I am stumped!   Any ideas, suggestions, or other wisdom would be much appreciated.



Edited by markp - 08 Jan 2018 at 8:13am

Yes, but it was working fine initially, so compatibility shouldn't be the issue. Additionally, I have it working from a pci-e riser connected to a pcl-e to m.2 adapter board holding my M.2 SX7000 in the same system which is a PCIe 2.0 x1 slot.

Not sure what I did, but now it's working correctly!?!?




Edited by markp - 08 Jan 2018 at 8:14am