Copper is actually ~25-250X leas efficient at transferring heat than a heat pipe and convection is hundreds of times more efficient than radiation at transferring heat and the fins on a heat sink would have hundreds of times less surface area for dissipating heat all that is to say this might work but it would be orders of magnitude less efficient than a standard heat sink.

Water moving is much better at removing heat than heat pipes could ever imagine. It depends on how fast the mass of water is moving.

What do you think heat pipes contain? Basically the same thing as water cooling systems.

Water cooling is basically a misnomer - it’s basically a heat relocation system that that gets the heat moved to what are usually air coolers that pass the heat off into the air. If the airflow in your PC is ideal and smart enough, no need for water cooling, you can air cool at the source at nearly the same efficiency, no need for a pump. It’s not as easy to manage in terms of space, but it has less maintenance issues.

I mean to say that a heat pipe not only contains less water per unit area for the phase changing cycle, since its under vacuum, but also the cycle only works at a particular heat per unit volume and temperature range. If you go past the temp range you get runaway.

Water in an active cycle has an almost unlimited ability to relocate heat. You still need to give that heat to something else, but you can pass a kilo of water thru a tiny labyrinth of fins at the heat source and a large surface area radiator with fan on the heat sink side. Vs a few ounces of water trapped inside a pipe running as a heat engine basically. Active pumping is brute force. At some point you won’t be able to contain the water pressure if your source is too hot, but there are many different working fluids.

Its irritating when we try designing a new cooling system at work and some guy will always want a heat pipe when clearly there is only a narrow band where those things are effective. Specially annoying if you don’t have control over the heat source. If you did have control over the source, then maybe you can tune it for a heat pipe. Car engines don’t have heat pipes. Solar collectors don’t use heat pipes either for the most part. Heat pipes need a constant source of heat that always stays below their max bandwidth.

I feel the need to point out that water cooling has an upper limit as well. If you get things hot enough, the water is going to flash into steam, at which point it’s going to decimate whatever system it’s in.

You can add additives to prevent that, but at some point it’s no longer “water”.

Reading this back, I suppose this is pedantism. But still.