Question GPU instability at boot

Dec 13, 2022
Built circa 2018.
MB: Asus Prime Z370-P, BIOS version 3004 (updated yesterday, did not fix issue)
CPU: i5-8400
PSU: OCZ ZT650W (Inherited from previous build circa 2010ish)
RAM: Corsair dominator platinum ddr4 2x8GB
Storage: 2xHDD on SATA ports, 2xSSD M2 NMVe
Additionally, one BD drive on SATA.
Screens: Primary FHD (AOC Hero27) on DisplayPort with GSync and Secondary FHD on DVI (LG something 22")

At boot GPU outputs video to secondary monitor, against my wishes, but from what I've gathered can't do much about this since GPU will prefer output to DVI before anything else.

Timestamp A

As boot progresses, immediately after the ASUS logo with the windows spinning ball, the secondary monitor displays some weird interference appearing as thin static horizontal line on black background resembling the windows load ball in size (except it goes all the way from side to side, and is just pure thin static) thing about a quarter of the way down the screen. Then the screen blinks. Windows login screen appears normally, except only on secondary monitor.

Timestamp B

After a few seconds, secondary monitor will blink again, primary monitor will turn on, and system will appear as normal on both primary and secondary monitors, as it is supposed to do, except windows transparency on primary monitor does not work properly until I restart explorer.exe, so I do it.

I also use a HWInfo+Rainmeter combo, and usually after this HWinfo will only recognise two data from NVIDIA until I also restart HWinfo. I also have to reconfigure the Rainmeter addresses to point to the proper NVIDIA data.

By now the computer is 100% online and issue-less.

Timestamp C.

Except sometimes it goes straight from timestamp A to C,i.e. boot without issue. I haven't managed to find any correlation regarding this, seems to be random.

Additional details:

After all this, sometimes on Task Manager I will have GPU0 as the Nvidia, sometimes GPU0 as iGPU and GPU1 as Nvidia.

If I quickly login while on timestamp B, task mgr will only display GPU0 as iGPU, and will add the Nvidia after the blink.

I did not have problems until two modifications a few weeks ago. In a span of a few days I added the secondary monitor (no issue at first, but can't be certain) and the second NMVE on slot M2_1. I had to fiddle with the BIOS to get it working because it appears enabling two M2 is off by default on this MB. I suspect it is likely related to the second M2, and I intend to disable it and boot the system a few times to see how it goes, but I'd still be clueless on what to do to fix the issue since, you know, disabling the M2 doesn't seem like the proper solution. Windows runs on M2_2.

Thanks in advance.



"PSU: OCZ ZT650W (Inherited from previous build circa 2010ish) "

Likely suspect.

Any way to borrow another known working PSU from a family member or friend to test in your build?

Otherwise try the following:

Power down, unplug, open the case.

Clean out dust and debris.

Verify by sight and feel that all connectors, cards, RAM, jumpers, and case connections are fully and firmly in place.

Physically inspect for any signs of damage.

Hopefully just a connection, etc. that has wiggled loose. Eventually warms up, expands, and tightens.

Could be inside the PSU and therefore not repairable.