Ryzen 7800X3D - Failure to POST / Code 00 after stress / when hot

[Easa]

Hello,

I have this weird problem with my custom rig - Ryzen 7800X3D, delidded and mounted with TG Frame on MSI X670E Carbon WIFI. Cooled by Aquacomputer Kryos NEXT, custom loop etc, not important. Now, you can run anything on it for weeks, it is rock stable under load and in idle. Games, Aida, Prime, Passmark, etc you name it. There is one thing though. When I want to shut down or restart the computer once the coolant is heated to operating level (around 40-45°C, i prefer low noise), for instance after a longer gaming session, it will no longer post. Does not matter if it ran for half an hour or a week. I must always wait 5-10 minutes for the computer to cool down, then it posts properly and everything works again. Temperatures are not the problem, nothing overheats. It does not act like this when I restart it on idle or when I let the coolant cool down to 35° (or less) after stress, before restarting.

Tried different mounting pressures
Tried reseating CPU
Tried reseating waterblock
Tried several BIOS settings, also defaults
Tried different memory sticks

Now, is the CPU defective, or its my motherboard doing this? I think it is the CPU, but I would be glad to hear second opinion on this.

 

[P4-630]

i prefer low noise

Maybe it's a safety thing, try using a different fan/pump profile in the BIOS.

 

[Easa]

No, it is not a safety thing, but thanks anyway.

 

[phanbuey]

It sounds like a memory training issue. How long does it take to post on cold boot?

What is cooled by the loop is it just the CPU?

Honestly it doesn't make sense that it's tied to temperature.

 

[ir_cow]

Very strange. So it is just not getting past the post code or does it go to a fail boot BIOS screen?

The first thing I would do is remove all overclocking settings including memory and see if it happens again. You can start to narrow down the problem that way.

Also update the BIOS to the newest.

 

[Vya Domus]

Are you sure it's not just the notorious AMD memory training ?

I sincerely doubt this is related to cooling, that being said 45C coolant temperature is very high, I understand you care about noise but what's the point of going custom loop if you are not getting any of the cooling potential, I bet the CPU is running at tjmax all the time under load with coolant temp that high.

Edit : Now that I think about it, it might be related to cooling. Do you have fans/pump plugged into any of the CPU fan headers ? Maybe when the temperature is very high on boot and it detects nothing in those headers it freaks out, I doubt it but maybe it's something like that.