Random rebooting during POST, stable in Windows

Prizm

Chassis Packer
Original poster
Jan 27, 2019
14
3
I put together a new build and have had some odd occurrences that I'm unsure about: Some reboots during POST, and odd M.2 drive behavior. Unsure if one is related to the other. No reboots or blue screens within Windows itself. I don't overclock any components.

Streacom DA2 case
ASRock Z390 Gaming ITX
2x16GB Corsair 3200 LPX
1x Samsung 970 Evo Plus NVME M.2
1x Samsung 860 Evo SATA M.2
Corsair SF600 SFX PSU
Intel 9600K CPU
Noctua NH-L9X65 (low profile cooler)
RTX 2060 Founders Edition


1. During first boot, my PC rebooted two seconds after power on, and continued rebooting at least a couple times before I shut it down. I pulled it all apart and put back the components back one by one and each time the PC successfully booted in BIOS. The last component was the second SSD drive (Samsung 860). When I put this in, the PC rebooted two seconds after power on again. I removed the M.2 screw and rescrewed it, and PC then booted ok. Maybe the M.2 drive is related to the reboots?
After installing Windows and trying a little gaming (with no restarts), I read that an immediate reboot is possibly caused by RAM setting incompatibility and that the motherboard may force a reset in order to find a stable RAM setting. This is possibly the problem. As a side note, I noticed the RAM was set at 2133, so I changed it to 3200 which is what it's rated for. PC still booted ok.

I then upgraded the BIOS from version 1.20 to 1.50 in case this would help. When the PC rebooted after BIOS upgrade, it reset after 2 seconds - the problem was back! But it only reset once, and the second time it booted with no problem. Was it a result of the BIOS being reset back to default settings? After a couple successful boots, I went back into BIOS to change the RAM speed again from 2133 to 3200 (since the BIOS had been reset to default). Since then I've had no further issues, but I'm still not totally sure what the issue was.

2. [EDIT: possibly resolved] The second problem occurred with the same Samsung 860 M.2 drive that I thought may have caused the reset problem above. I installed Windows accidentally on the 860 SSD, but was unable to reformat it using Windows' own programs. After installing Windows correctly on the 970 instead, I used a third party Windows program to format the 860 SSD as exFAT.

I rebooted the PC after the format and my system reported no boot drive. Wait, what happened to my new Windows installation on the 970? I double-checked the BIOS and the boot drive shows as the 970. But my PC still insisted it's not bootable. I thought, screw it, I'll just install Windows again on the 970.
So did I format the wrong drive? No, because I labelled the 860 with a name when I formatted it, and I could see the name. So I did format the right drive. Who knows WTF happened. Something cocked up the MBR/GPT on the 970?

Now here's the next issue: after formatting the 860 and using it for a bit, I attempted to delete a 2.5GB MKV on it and nothing happened. [EDIT: Solved unable to delete MKV, see post below]

That brings me to today. I have used CrystalDiskInfo to do a test of the 860 disk and it seems ok, showing 100% good health.


My current thoughts:
- The rebooting was RAM setting related (not necessarily defective RAM, just a mismatch between RAM and motherboard). There have been no resets or blue screens in Windows, indicating it's not a RAM quality error or a PSU problem. The weird thing is, the RAM is standard stuff and nothing special. ASRock boards shouldn't have a problem with it.

- The 860 SSD was possibly screwed up by the third party program I used to format it as exFAT (that was also when the format somehow affected the booting of my 970). Being unable to delete the MKV was possibly a side effect of a dud format, or it was just a random error that was just bad luck and bad timing.
 
Last edited:

Prizm

Chassis Packer
Original poster
Jan 27, 2019
14
3
PARTLY SOLVED: I have found the problem with not being able to delete the MKV file. I had installed the latest test version of Windows 10, and there is actually a bug that stops MKV files from being deleted/moved/renamed. You have to go into Safe Mode to be able to delete the file.
 
  • Like
Reactions: BaK