If you are experiencing an audible bubbling or rattling noise from your Kraken cooler, this could be a sign of air trapped within the pump or a failing cooler.

Before Starting - Check the Fans

A good place to start before going for the pump is to check the fans.  A clicking or rattling noise from the PC is more likely to be from the fans rather than the cooling pump.  The best way to check this is to manually stop the fans.

If your fans are connected to a CAM controlled header, you can adjust the fan speed from the CAM software itself while the PC is running.  Open the Cooling tab and select the fan(s) you wish to adjust.  Set the mode to Custom and pull the dot on the far right of the chart to the bottom to stop the fan.

Gently press on the center hub of the fans to slow them to a stop.

If your fans are not connected to a CAM controlled header, you may need to manually stop the fans.  With most fans, this can be safely done by pressing the center of the fan hub until the fan stops spinning.  Do not attempt to stop the blades directly.  If you have high performance fans however such as the NZXT Performance Series (F120X, F140X, etc.) do not attempt to manually stop the fans as this can result in severe harm.

If the noise is no longer present after stopping a fan, this means the fan itself may be defective and needs to be replaced.  If these are the fans included with the cooler or other NZXT fans, reach out to our Customer Support team for help with a replacement (under warranty).

Checking the Pump (Pump Speed)

The most reliable way to check pump noise is to try adjusting the Pump Speed.  This method is only recommended for CAM powered coolers as shown in the list below:

* The H1 (2021) AIO is controlled through the integrated controller, not directly through the pump itself.  The H1 (2021) AIO does not feature lighting controls
** The Kraken 120 only features lighting control when connected directly via the 4-pin NZXT RGB connector to a compatible controller.

To adjust the Pump Speed, set the mode to Custom and pull the dot on the far right of the chart as low as it will go.  If the noise changes, this indicates a potential issue with the pump.  If the noise remains consistent, there may be another source of the noise.

Can I adjust the speed for non-CAM AIOs such as the Kraken Core or Kraken 120?

We generally do not recommend adjusting the pump speeds of the Kraken Core, Kraken 120, or Kraken M22 below 100% as this can cause issues for the longevity of the pump itself.  While you can temporarily adjust it to check for noise via the motherboard BIOS, we do not recommend changing reducing the pump speed for long periods of time.

Clearing Pump Noise

As noted at the start of the guide, the most common source of pump noise is air finding its way into the pump assembly.  All AIO liquid coolers will include some air in the loop in order to allow for changes in pressure as the cooler heats up and cools down.  This can sometimes find its way into the pump which is not ideal, however it is pretty easy to work this air back into the radiator.

Step 1 - Release the Pump Cap from the CPU

Before releasing the pump cap, we recommend disconnecting any cables from the Pump Cap to make it easier to move.  Many Kraken coolers will feature detachable breakout cables which can be disconnected directly from the pump while those with integrated cables must be disconnected from the motherboard and/or controller.

* The Kraken M22 features a removable USB 2.0 cable (at the Cap) and integrated 3-pin Pump cable (at the motherboard).
** The H1 (2021) AIO features two cables, a standard 3-pin Pump Cable and a dedicated connection for the integrated Controller.

The Kraken Elite (2024) features a breakout cable at the radiator itself, so no cables need to be detached.

With the cables disconnected, remove the thumb screws holding the Kraken in place.  Most models will feature four (4) screws as shown above, however some models may only feature two (2) screws located at the top and bottom of the socket.  For two screw models, the screws only need to be loosened and not removed.

Do not touch the thermal compound on the pump cap or CPU.

Step 2 - Shake the Pump Cap

Kraken removed from case for demonstration purposes.

As shown in the video above, position the pump cap below the radiator and shake the cap vigorously for 30-60 seconds.  You do not need to remove the radiator from the case, however for more compact builds such as the H3 this may make the process easier.

Step 3 - Reinstall the Pump Cap

Position the Pump Cap over the CPU heat and re-secure it using the four thumb screws.  These should be tightened evenly in an X pattern as shown above.

Step 4 - Test the Pump

Once the PC is started again, set the Pump Speed to 100% (for CAM powered Krakens) and allow the system to run for at least 4 hours but ideally overnight at this setting before changing the pump speed.

If the noise does not fully go away, repeat the steps above to see if there's any further improvement.  If the noise continues or gets worse, this could indicate a failing pump which will require replacement of the AIO cooler.