Is My AIO Cooler Failing? How to Diagnose It

Short answer: Check the idle temperature in your BIOS first. A healthy system idles around 30 to 40 degrees; anything above 70 at idle points at a cooler fault. Then check the pump RPM in the BIOS. If it reads 0 or N/A, the pump is not getting power or has seized. Normal RPM with high temperatures instead points at mounting pressure, dead fans, or a dust-clogged radiator.

Higher temperatures than usual, sudden shutdowns under load, or grinding and clicking noises from the cooler all point the same direction. The useful thing is that an AIO has only three places it can fail, and you can check all of them in about ten minutes without removing anything.

What counts as overheating

A PC is overheating when the cooler cannot hold it in a safe operating range. Components get genuinely hot in normal use, reaching 100 degrees and beyond depending on the part.

When a system overheats, the CPU starts thermal throttling, reducing voltage and performance to bring temperatures down. If that does not work fast enough, Over-temperature Protection cuts the system off to prevent damage. Common triggers:

• The cooler does not have enough capacity for the CPU, for example a Kraken 120 or Kraken M22 on an AMD Ryzen 9 or Intel Core Ultra 9
• Air is not moving through the radiator because of dust or debris
• A part of the cooler has failed, usually a fan or the pump

What is a safe temperature?

It varies by processor, and the number that matters is the Thermal Junction Maximum (TJ Max) for your specific chip.

Figures from AMD and Intel product pages as of November 2025. Hitting these numbers under heavy load is not automatically a fault. Hitting them at idle is.

Step 1: Check the idle temperature in the BIOS

The BIOS is the best place to check, because the CPU is under minimal load there and nothing in Windows is skewing the reading. Press Delete at the startup splash to get in.

A properly cooled system will idle somewhere around 30 degrees. Normal idle varies by build, but 70 degrees or higher at idle is the clear signal that something is wrong with the cooler.

Step 2: Check the pump RPM

This is the single most diagnostic reading you can take. Pump RPM is reported to the motherboard over the 3-pin pump sense or pump power cable, and you read it in the BIOS.

Which header it should be on depends on your cooler:

• CPU_FAN for coolers with integrated fan control: Kraken Elite, Kraken Plus, Kraken (2023)
• AIO_PUMP or CPU_OPT for coolers without it: Kraken Core, Kraken 120

A working pump reports a real number, typically around 3200 RPM. If it reads 0 RPM or N/A, the pump is not getting power or has seized. Check the connections for your model:

If the connections are good and it still reports nothing, you are looking at a failed or seized pump.

Step 3: Noisy or seized pump

Loud clicking or grinding usually means air has collected in the pump cap, letting the pump collide with its own housing. It is often fixable:

1. Confirm the pump cap sits below the highest point of the radiator. If it does not, remount the radiator. This is the root cause more often than not.
2. If mounting is correct, remove the cooler and shake the pump head, held below the radiator, for one to two minutes.
3. Reinstall and set the pump to 100% in CAM (on CAM-enabled models).
4. Leave it running at 100% for at least four hours, ideally overnight.

Repeat once if it improves but does not clear. If the noise survives a second attempt, the cooler needs replacing. Our full walkthrough of pump noise covers the shake technique in detail, and radiator placement covers the mounting rule.

A high-pitched electrical whine is different. That is coil whine, and it is normal.

Step 4: Check CPU contact

Every NZXT Kraken ships with pre-applied thermal paste, which makes this easy to check. Unscrew the pump cap and look at whether the paste has spread from the cold plate onto the surface of the CPU.

If the thermal compound is still intact and unspread, the cooler was not making proper contact. Check that you used the correct backplate and standoffs for your socket, per the manual that came with the cooler.

Step 5: Check the fans

Fans are binary. They work or they do not.

First confirm they are connected correctly: to the breakout cable (4-pin PWM or 8-pin NZXT) on the Kraken Elite, Kraken Plus, Kraken (2023) and Kraken Z, or to a motherboard header on the Kraken Core, Kraken 120, Kraken M22 and Kraken X3.

If they are connected and not spinning, power off, disconnect the fan and spin it by hand. A healthy fan spins freely and coasts to a gentle stop. If it stops abruptly or you feel resistance, the motor has seized and the fan needs replacing.

Step 6: Check the radiator

Clean the fins of dust and debris with compressed air and a brush. A clogged radiator is a very common cause of gradually worsening temperatures, and it is the cheapest fix on this list.

Then power on and feel both tubes. A minor temperature difference between them is normal. A major difference suggests a blockage in the loop.

Signs of an internal blockage

Kraken coolers are closed-loop systems and are not designed to be drained or refilled. A blockage shows up as:

• Idle temperatures above 75 degrees
• Sudden shutdowns
• Badly degraded general performance, with programs and downloads slowing down

Do not open the cooler to drain or clean it. That is not covered under the limited warranty and will not fix it.

Quick reference

Warranty

All Kraken coolers carry warranty coverage from the date of purchase from an authorised reseller.

Frequently asked questions

What idle temperature is too high?

Above 70 degrees at idle in the BIOS is a strong sign of a cooler problem. Above 75 suggests a blockage. A healthy system typically idles around 30 to 40.

My pump RPM shows N/A. Is the pump dead?

Not necessarily. Check the sense cable is on the right header for your model, and that the header is not disabled. On Kraken Core and Kraken 120, the header must also be set to 100% fixed speed. If connections are correct and it still shows nothing, the pump has likely failed.

Can I clean or refill my AIO?

No. Kraken coolers are sealed closed-loop systems. Opening one is not covered by the warranty and will not resolve a blockage.

How do I know if it is the cooler or the CPU?

Idle temperature in the BIOS is the cleanest test, because the CPU is doing almost nothing. If it is hot while idle, the problem is heat removal rather than heat production.

Why are my temperatures fine at idle but bad under load?

That points at cooling capacity rather than a fault: dirty radiator, fans not ramping up, or a cooler that is undersized for the processor. Clean the radiator and check the fan curve first.

Does a seized fan mean I need a new cooler?

No. Fans are replaceable separately. If they are NZXT fans in warranty, contact support about a replacement.

Need a hand?

Send us your BIOS idle temperature and pump RPM reading and our team can usually tell you straight away which of the three it is. Reach them at NZXT Support.