Noctua does not do liquid coolers. Computex revealed a prototype of a liquid cooling product, but even today it is not. Naturally, air cooling companies do it in a completely different way than the standard. That liquid cooler has no pump.

Noctua's design wants to provide effective cooling, despite the lack of this 1 key component. Rather than pump up the cold plate or embedded beside the radiator, the Noctua design utilizes a two-phase thermosiphon.

"Do you think you are familiar with the basic concepts of thermal siphons and are fluid circulation created by the difference in density due to heat input?"Noctua representative Jakob Dellinger asks me.

"Yes," I reply with confidence, but Dellinger explains to me the details anyway. Here's how it works — for your benefit, not mine. Obviously.

"So in Italy or Greece, you see those rooftop water heaters"Yeah, thermosyphon base heats the water and then starts circulating. And that's exactly what happens here, except for the difference that it is a two-phase thermal siphon."

"So when the working fluid is on the CPU, it evaporates and it cools off, condenses back into a liquid state and eventually returns back to the evaporator to evaporate again."

Sounds like how a heat pipe works with a GPU or CPU cooler— something Noctua knows very well. What are you doing? Nevertheless, it has partnered with an aviation cooling company called Calyos to work on the thermosiphon project.

"The reason this is a very promising technology is due to the latent heat of vaporization.

"So, when you have a pot of water, it may take 10 minutes to boil it, but it will probably take 2 hours to evaporate the entire amount of water. Therefore, its phase change process has much more heat capacity. And this is what we are using here for cooling."

Effectively, it can absorb a lot of heat before evaporation occurs. This is the headroom for shifting heat from the power-consuming CPU.

The goal is "AIO-level performance", but there are no disadvantages of AIO coolers. Basically, the absence of a pump means there is no risk of pump noise, vibration, or failure.

Although the thermal siphon has 1 potential drawback. It depends on gravity. To work, a 240mm or 360mm radiator must be top mounted in the chassis. Also, it's not so much a disadvantage in itself, but the radiator of the thermosiphon prototype still comes with a fan — if you wanted something completely passive, you would look best elsewhere, like the NH-P1.

Anyway, it is one helluva concept. Noctua doesn't put an eta when it's likely to arrive, but the prototype "already looks very good.""