PC Pre-Post boot-cycle

[Fixxer8]

Hi, my current PC build which ive had since last 2019 ( and up until january 2022 ) has been problem free, but in january it started behaving oddly. What happened once every 2 months ish, was that when i turned the pc on - the fans would spin up, and stay in such state for about 20 seconds before the pc turned off. Then it turned on, followed by 2-3 reboots until it cooled off and booted normally. 

 

Specs:
Gigabyte Aorus Z390 Wifi Pro ITX rev 
i9 9900k
32GB Corsair Vengeance Pro ( CMW32GX4M2Z3200C16 )

Samsung 970 PRO

GA RTX 2070OC

1. I had home-office for the entirety of 2020-2021 ( home 3 days pr week, turning my pc on every morning) no issues. 

2. BIOS updated to latest F8 version

3. The only thing i can come to think of is that i may have activated XMP earlier this year. But, would that cause spontanius pre-post boot cycles that occured once every two months ish?
4. Aida 64 stability test ran for 4 hours, so with 3Dmark's stability test. 

 

Not had any random crashes in gaming sessions

 

Ive now turned off XMP 
(as a sidenote, the ram-sticks are not on the QVL for my MB)

Is it the "memory training" that kicks in? And perhaps some sort of compatibility issues?

[emosun]

More than likely it's just powering on in a state that yields no post due to a bios issue , such as having some sort of unsupported setting. it then reboots itself to either switch to the second bios or just resets the main bios to default.

I'd just set the bios to be 100% default and see if it still happens in that configuration.

[Fixxer8]

Sounds like a plausible explanation - but why just once every now and then i wonder.
I would expect it to do so every time with XMP on. But i do not have any knowledge of the deep systems of a motherboard. Ive disabled XMP for now, so ill see what happens.