Long story short my computer was unstable for 3 month with constant restarts of the computer during gaming and recently it even started with all kind of windows 10 bugs and blue screen of death.
But i am happy to say that i findly found the reason for the system instability.
When i got my new 5900x cpu and the 6900xt graphics card i also bought a new AIO water cooling system named Castle 360 v2.
To replace my old AIO water cooling system.
The new system was a bit different since the AM4 metal mounting brackets/plates that you install on the cpu cooler is rather wide.
This result in the AM4 metal brackets touch the capacitors next to the cpu. The metal bracket touches 2-3 capacitors, and it also touch the m.2 NVME harddisk if you have one installed.
As you might know metal can move electricty from a-b and i think that is what happen to my computer and this made the hardware fail since it "maybe" got some electricial impulses/voltage that it should not get.
I am no expert how and what can short in a pc and what materials can do this or even if they do.
But i can say one thing... When i remove the castle 360v2 AIO and installed my old corsair 115 AIO water cooling system with another smaller type of am4 cpu mounting bracket then all of my blue screen of death and windows errors stop pretty much instant.
So if you have problems check if your cpu coolers metal parts are touching anything, this might be a "hidden" problem that most people overlook.
Els now i have to see how stable the pc is now ( more test and using it )
But so far so good.
i hope this helped some of you.
Alternative if your pc shuts down.
It can be your ram is not "compatible and that you have to adjust the speed and voltage to make the ram stable.
Regarding your cpu, i fond that setting the voltage to 1,375volt instead of auto make it stable but will slow it down.
If i set it to 1,4volt it perform better.
But all in all i would expect ram and cpu to work out of the box on auto after selecting factory default, but in my case it does not in my case. I dont know if my hardware is defective i had this issue from day one, even before i installed the above water cooler.
But if i select xmp in bios for the ram, and 1,375 or 1,4volt for the cpu-vcore insted of auto then the pc is stable.
Other people talk about turning of something called cpu c-state might help.
Other say in windows 10 turning off hibernation in the power plant and fast boot help.
Some say setting your harddrive to NEVER to go into standby/sleep mode also help.
Well the forum is full of good advice.
Check if your cpu metal mounting bracket is touching any other componments in the pc.. If it does that Might be the problem that create instability crashesa and errors. This is a castle 365 v2 AIO water cpu water cooler.
Its rather easy for the metal parts to touch stuff inside of the pc since there is very little room for error when