Just guessing since the article was information deficient: mainframes. They’re so expensive anyway that adding on a closed cycle cryogenic cooler isn’t even in

Just guessing since the article was information deficient: mainframes. They’re so expensive anyway that adding on a closed cycle cryogenic cooler isn’t even in the top ten line items on the bill. At cryogenic temperatures, even older architectures not optimised for it can hit 9 GHz. An optimised modern CPU could probably run at well over 10 GHz, which is a big performance boost for legacy single-threaded code. Cooling and “overclocking” the CPUs would be cheaper than rewriting the code. More extreme frequencies (over 100 GHz) can be achieved with existing but more exotic digital electronics such as Rapid Single Flux Quantum (RSFQ), which uses liquid helium cooling. This is used in some military radars, radio telescopes, and a few other similar high-speed signal processing scenarios. If ordinary silicon could run at, say, 20 GHz with cheaper LN cooling, that would lower the cost of some fancy radars.