Where Should You Mount an AIO Radiator? Top, Front, or Bottom

Short answer: Mount the radiator in the top of your case with the fans set as exhaust. If your case cannot fit your radiator up top, the front is the next best spot. Do not bottom-mount an AIO. The rule that matters more than any of this: the highest point of the radiator should always sit above the pump cap.

Radiator placement is one of the few build decisions that affects how long your cooler lasts, not just how cool it runs. Get it wrong and air collects in the pump, which is where the gurgling noises and the early failures come from. Here is how to think about it.

The one rule that decides everything: keep the radiator above the pump

Every AIO liquid cooler ships with a small amount of air in the loop on purpose. It gives the coolant somewhere to expand into as the system heats up and cools down. That air has to live somewhere, and you want it living in the radiator.

If the pump ends up as the highest point in the loop, air migrates into the pump housing and stays there. A pump running on air instead of liquid moves less heat, makes more noise, and wears out faster. So whatever mounting position you choose, check the same thing: is the top of the radiator higher than the pump cap on your CPU? If yes, you are fine. If no, move it.

Top mounting: the default answer

If your case supports a top mount for your radiator size, take it. Two reasons:

• The radiator sits above the pump by a comfortable margin, so trapped air has nowhere to go but up and away from the pump.
• Heat from the coolant leaves the case immediately instead of being pushed across your other components.

Set the fans to exhaust, pushing air up through the radiator and out of the case. This is the configuration NZXT recommends for top-mounted Kraken coolers.

Case support varies by size. The H9 Flow takes up to a 420mm radiator in the top, the H5 Flow and H7 Flow handle common 240mm to 360mm sizes, and smaller cases step down from there. Check the radiator support list for your specific case before you buy a cooler, because a 360mm radiator in a case rated for 280mm is a returned order.

Front mounting: the good alternative

If the top of your case will not take your radiator, mount it in the front. NZXT refers to this as a side mount, and it is a genuinely fine option rather than a consolation prize. Plenty of cases fit a larger radiator in the front than they do in the top, so front mounting can actually get you more cooling surface.

The one thing to verify is still the pump rule. In most mid-tower cases a front-mounted radiator sits well above the CPU socket, so you are covered. In a compact or ITX build, measure it rather than assuming.

Should the tubes go at the top or the bottom?

This is the most argued-about question in AIO installs and the honest answer is that it comes down to preference. Tubes at the bottom can be quieter, because you are less likely to hear a trickling sound from coolant moving through the radiator. Tubes at the bottom is also easier to route in a lot of cases. Neither orientation will meaningfully change your temperatures.

Pick the one that makes your cable routing cleaner and stop worrying about it.

Why you should not bottom-mount an AIO

Bottom mounting puts the radiator below the pump, which is exactly the situation the pump rule exists to prevent. Air in the loop collects at the highest point, and if that point is your pump cap, the pump is running on air.

The symptoms show up as a bubbling or rattling noise from the cooler, higher CPU temperatures than the cooler should deliver, and a shorter pump life. It is not an instant failure, which is why people get away with it for a while and then post about it six months later. NZXT does not recommend bottom-mounting a Kraken radiator in any configuration.

Does radiator position actually change my temperatures?

Less than most people expect. Radiator size and fan setup drive cooling performance far more than whether the radiator is in the top or the front. A 360mm radiator in the front will outperform a 240mm in the top.

Where position genuinely matters is airflow direction and longevity. A top-mounted exhaust radiator dumps CPU heat straight out of the case instead of feeding it to your GPU. And correct positioning relative to the pump is what keeps the cooler healthy over years, not weeks.

Quick reference

Frequently asked questions

Can I mount my AIO radiator in the front as intake?

Yes. Front intake pulls cooler outside air across the radiator, which is good for CPU temperatures, though it does raise the temperature of the air reaching the rest of your components slightly. Front exhaust does the opposite. Either works, and the difference is small in a case with reasonable airflow.

What happens if the pump is higher than the radiator?

Air in the loop collects in the pump. Expect a bubbling or gurgling noise, reduced cooling performance, and a shorter pump lifespan. If you have already built it this way, remount the radiator higher rather than living with it.

My AIO is mounted correctly but still makes noise. What now?

Air can still work its way into the pump even in a correct install. It is usually fixable at home by releasing the pump cap and shaking it to move the air back into the radiator. Our full walkthrough is in why your AIO is making a gurgling or rattling noise.

Does tube orientation affect cooling performance?

No. It can affect noise slightly, with tubes at the bottom generally being quieter, but it does not change thermal performance in any way you would notice.

How do I know which radiator sizes my case supports?

Check the specifications for your case model. Radiator support is listed per mounting position, so a case may support 360mm in the front and only 240mm in the top. NZXT lists this on every case product page and in the manual.

Still stuck?

Our support team handles this every day. Head to NZXT Support and we will help you work out the right position for your case and cooler combination.