Watercooling without pump or noise: where Noctua's crazy bet really stands after two years of prototypes

Do you have watercooling on your PC? An AIO or custom? You see, that little noise. A low hum, neither really loud nor really discreet, coming out of the watercooling. It's the pump. We end up not hearing it anymore, except on evenings when we can't sleep. Noctua, cult manufacturer of its brown and beige fans, has decided that this noise no longer exists.

The idea is called thermosiphon, and the brand has been pushing it since Computex 2024. The principle: no pump at all. The liquid heats up on contact with the processor, transforms into vapor, rises to the radiator, condenses there, then descends by gravity. Everything relies on this cycle, without a single moving part in the loop.

Last year, the prototype received around 100 watts on a Ryzen 7 9800X3D, which is the load of a rather moderate processor. At Computex 2025, in Taipei, Noctua connected a Ryzen 9 9950X3D pushed to 230 watts, its absolute maximum where its nominal power caps at 170 watts. And there, surprise: the thermosyphon held.

The thermosyphon is not a 100% in-house project: Noctua is developing it with Calyos, a Belgian specialist in two-phase cooling used to the aeronautics and automotive sectors. Which explains why a manufacturer historically attached to air finds itself handling steam under the hood.

Two degrees is all that separates them

At the show, in 2025, two screens displayed the temperatures side by side. The thermosyphon stabilized the chip at 81.4°C. Right next door, Noctua's future in-house AIO, the NL-LC1, displayed 79.4°C. Two degrees of difference under a brutal load is what Noctua engineer Jakob Dellinger sums up by neck and neck, in other words neck to elbow.

Small asterisk anyway: it specifies that if we switched the AIO pump to silent mode, the thermosyphon would go back to the front. Clearly, the tie holds in part because the AIO is running at full speed. The fact remains that for a system without a pump, without wear and without possible breakdown on this side, it is a real leap.

Alongside this pumpless project, Noctua is preparing a more classic AIO, the NL-LC1, developed with Asetek on the Emma V2 platform. It was this model that served as a reference in the salon comparison. Available in 240, 360 and 420 mm, it should arrive well before the thermosyphon, with prices announced around 220, 250 and 280 euros depending on the size of the radiator.

To go further

Noctua finally gets into watercooling after twenty years of fans

A product that will not arrive before 2027, at best

It's not that simple. The radiator must be mounted at the top of the case, gravity requires, which closes the door to a lot of configurations. The system targets the 360 ​​mm format, because maintaining this performance at 240 mm remains a headache. And there are three fans left on the radiator, so we forget about absolute silence. Above all, Noctua remains at the laboratory stage and recognizes that reproducing this level in mass production is the real challenge. “We are still at the laboratory stage,” confides Jakob Dellinger: the next challenge will be to achieve this level of performance not on a prototype, but consistently in mass production.

Noctua is clearly playing a patience game. The release would not be expected before the third quarter of 2027, an estimate that the brand itself describes as flexible. Translation: don't hold your breath. But for once, the prototype looks like a product, more like a show promise. If Noctua keeps his bet, the silence will have a name, and it will no longer make a sound.

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