Question ASUS Z170-A - Memory Boot Issues

fletch254

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Dec 7, 2013
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TLDR: 16GB RAM modules were working fine on ASUS Z170-A motherboard until BIOS reset and firmware update at which point I no longer get POST.

I recently purchased 4x16GB RAM chips from Corsair at the same time I bought an NMVe M.2 drive. I installed the RAM on the day I got it planning to do the M.2 installation at a later point and all worked fine. Everything booted as expected, both BIOS and Windows were detecting the new configuration and everything ran like a charm for a couple of weeks.

At the point I got around to installing the M.2 drive I ran into a few issues with my BIOS not allowing me to boot from the M.2 at all no matter if it was the only drive or not. After about 2 days of faffing around with it, I finally decided to call it quits and just go back to my SSD with the 64GB RAM, only at this point I noticed that even my old SSD wasn't booting with the 64GB RAM (No POST). Whilst trying to get the M.2 to run I had reset the CMOS and even installed the very latest BIOS firmware updates thinking that either of those might have been causing the boot issues with the M.2 but it turns out that at some point, the RAM had become the issue and not the M.2.

I know this because I am now running my M.2 fine with no problems, yet cannot boot from either the M.2 or the original SSD when using any of the 16GB chips. I've done a lot of debugging of this myself over the past week or two (I will outline my steps below) and have deduced that at the point I reset & upgraded the BIOS I have lost some configuration somewhere that is stopping the system booting with the RAM installed. I am able to boot back into the system when I use my older, 8GB DDR4-2133MHz chips (x2).

If anyone has had any similar issues or knows any starting points to look at for potentially fixing the issue it would be greatly appreciated as I'm just hitting dead ends with everything I try.

Debugging steps taken so far:
  • Attempted to boot with each RAM module individually
  • Attempted to boot with every combination of pairs of modules in case it was dual channel only fsr
  • Cleared CMOS after each attempt.
  • Tried the ASUS Z170-A default settings.
    • Here I also tried manually setting the RAM speed to 3200MHz as I noticed that the BIOS is reading it as 2133MHz which it isn't.
  • Looked into enabling or disabling any XMP profiles on the modules (none existed)
  • With compressed air I cleaned all of the RAM slots on the Mobo in case of dust or anything like that.
  • Ran PassMark's Memtest86 allowing 13 passes and received no errors (screenshots attached).
As a side note I'm fairly certain that the RAM I have purchased is compatible with the rest of my system. One, because it had been working no problem before the BIOS update and reset, and two I ran the Crucial System Scan before purchasing which I believe checks compatibility of parts before suggesting potential upgrades.

Any help would be greatly appreciated

Karl

Passmark Results
(Realize now I can't attach images but here's the important stuff)
  • RAM Info : PC4-25600 DDR4 3200MHz / 22-22-22-52 / Crucial Technology CT16G4
  • Tests Passed : 11/11 (100%)
  • Bits in Error - Total: 0 Min:0 Max: 0 Avg: 0
  • Tests 0 -> 13 Errors 0