Question 5820k WC overheat after restart

May 27, 2020

I have a 5820k in an Asus X99 ii A motherboard with a Riotoro Bifrost 240 AIO WC.

When the machine is running it is great - Really low temps, even under stress.

If I restart the machine (Windows restart) it is fine.

If, however, I power the machine down and then power it up the temps go crazy. Sometimes it will just start working but it can be hours before it does (sometimes days and at the moment it seems like never lol).

So, we had to turn power off in the house this morning and when I turned the PC back on it just POST's with an overtemp error and the BIOS shows the CPU going to 100 within a minute of boot.

The white light is lit on the WC block.

I have tried reseating the CPU and the WC.

The actual WC block is getting super hot to touch (more so on just one side).

The pipes are not even warm and the rad is stone cold as well.

Does anyone have any ideas please ? This has been happening for about a year and I have replaced the WC 3 times (from H100 to Riotoro and then another Riotoro) - In this time the MB has also been replaced.


Jun 2, 2009
Sounds like the pump is dying/dead. You'll need a replacement.

As for why? What is your power supply? What are your system specs? Do you have a UPS? Where is the pump getting it's power?

I think that your power supply may be inadequate. because it's only happening on cold boot, I think the pump is not getting enough power on startup. Startup surges, for the pump and other system components are much higher than compared to a warm boot (restart) where most of the components are already running.

One way to check would be to plug the pump/AIO into another power supply on it's own. Alternatively you can unplug the motherboard and jump start the power supply to see if the pump starts up consistently.

I'm not familiar with the riotoro so you'll have to figure out how to determine if the pump is running or not. It might be easier to tell with it detached from the CPU. You might be able to feel the vibration of the pump or torque of the spinning head inside.