Asrock X99 ITX - Died by itself during the night.

Hey,

OMGawd, with the complexity of that build, which I cannot even really see in your pictures, what could be worse than the mother board failing... if it has.

What does "it runs the whole systeme except with the motherboard" mean?

I assume that means all the liquid cooling components are working and pumping fine, fans spinning, etc. That would tend to show the +12V rail of the PSU is working fine, since it is a decent enough load on the PSU. If the lighting you are using is powered from the +5V rail, then that rail seems to be working too, although not a high power load.

If the lighting is using +12V power, then we can say that the PSU is not being completely "tested", since the +5V and +3.3V rails are not being used. All this is just in an attempt to verify the correct operation of your PSU. PSUs like yours use the +12V rail to derive the +5V and +3.3V rails. That's a good design, but means those other two rails can have a component failure that does not affect the +12V rail.

Assuming you are using all new major components in this build, mother board, CPU, cooling components, memory, and PSU, regardless of their quality, any potential failures will occur early on in the use of those components.

For example, a bad part in a PSU won't be detected until the PSU is put into actual use for a period of time. The same can be said for the mother board, memory, HDDs/SSDs, etc.

Consider all the chips and discrete transistors, and other electrical components  in any PC besides those in the CPU. There are billions of them. A single bad part can make the entire PC non-functional.

That is why a PC can go from working perfectly, to utterly dead, over night, sorry to say. These part don't fail catastrophically all the time, they fail with a whimper, not a bang.

The PSU clicking sound could be one of its protection systems working, caused by a short circuit, for example. It also could be a relay used to jumper a part used only when a PSU has powered applied to it, for efficiency reasons, so not a problem. But it could also be a PSU problem.

My suggestions would be, first replace the PSU with another unit. That should be a relatively simple thing to do, given your build.

Prior to that, really checking the PSU cable connections at both ends should be done. The +12V CPU power cable would be the one I would check first.

Given the complexity of your liquid cooling system, a single tiny leak could ruin the board, as you know. When do these leaks tend to happen? Early in the life of the system, even if it was leak tested. A thorough and complete inspection must be done.

I know, you've done that already, you are sure all is well. I get that.

But if it comes to breaking down the PC to remove the board, please do that carefully so you will find any problem that could happen AGAIN. I know you don't want to do this even once, but twice or more? Of course not.

I see no Dr Debug display on your board. Do you have the POST code beep speaker installed?

Was this system over clocked at all? Or running at stock CPU settings?

I'm thinking about what else you can do, but that's all I have for now.