I’ve had quite the challenging experience with my Z690 system. Everything was running fine for about six months but then my water cooling loop Stopped working. I took out a radiator thinking I had too much resistance and restrictive flow and this marginally helped. So sort of unfortunate series of events, I decided to replace the stock CPU bracket with the thermal right support bracket and in the process I bent a few pins. I corrected the pin placement and was able to get them computer booting but then it began not posting soon after. Basically had nonstop issues with the system. I flushed out the water pump and the CPU block previously and shortened the cooling loop without taking it all apart. Unfortunately my problems persisted. This is the first time in a year that I took everything out of the case and disconnected the water lines from the motherboard and this is what I found; Please see the pictures. Does anyone know what this is? It doesn’t seem like any rust or oxidization process… but it has basically plugged the water cooling loop. I will admit that I don’t remember if I flushed it the motherboard before installing the water cooling for the first time.