Facepalm: Back in 2010, a company named Danamics sent out a handful of CPU coolers to various publications for review. The heatsink in question, dubbed the LMX liquid metal cooler, utilized a heatpipe design filled with liquid metal instead of a more traditional working fluid (like water).
Overclocking enthusiast der8auer recently got his hands on one of these rarities, and what an oddball it is. What makes it truly different from a traditional heatpipe-style cooler is the electro magnetic liquid metal pump situated at the top of the cooler. It also comes with a standalone controller board utilizing unconventional power connections, suggesting this may be an early prototype unit.
After getting his hands on the cooler's manual and reading up on it, der8auer learned that Danamics went with a sodium-potassium alloy. As noted in the manual, the alloy reacts violently with water and can cause fire or an explosion if released in large amounts.
Der8auer found that the sodium-potassium alloy is about 30x better at thermal conductivity compared to water, which might explain why Danamics thought it would be a good fit for a CPU cooler. In testing with an Intel Core i9-12900KS, the LMX performed about five degrees worse than a Noctua U12A under load in Cinebench R23. That is not terrible given its age but it's not great either, especially considering how expensive it was back in the day and that coolers half its cost could outperform it.
There is also the safety issue, and it is probably not much of a surprise that Danamics didn't ship any retail units. In fact, according to der8auer, the company shut down just a few months after introducing the LMX.
Nowadays, about the biggest concern involving retail CPU coolers is the potential for self-contained liquid cooling loops to spring a leak and damage your hardware. Personally, I still prefer to stick with traditional air-cooled heatsinks. Even if your fan dies, most modern systems will shut themselves down before any permanent damage occurs.