For the most part, all-in-one liquid coolers come in three general sizes: 120mm (single fan), 240mm (two fans), and 360mm (three fans). That includes Arctic's Liquid Freezer II line of AIO coolers, but apparently 360mm was not big enough for some customers, who have been urging the company to go even bigger. And it did, with its new Liquid Freezer II 420.
This is still a three-fan cooling unit, but with larger 140mm fans attached to the radiator instead of 120mm fans, as found on the Liquid Freer II 360 model. It exists because, according to Arctic, fans kept asking, "Will Arctic ever release the Liquid Freezer II in bigger sizes?" Why yes, yes it will.
From end-to-end, the radiator is actually 458mm long, but 420 sounds cooler (and coincides with the combined size of the three 140mm Arctic-P fans). Arctic says it is the company's largest and most powerful cooler to date, but that's selling it short. It's also one of the biggest AIO coolers ever made. The only other 420mm-class AIO I can think of is AlphaCool's massive and refillable Eisabaer unit. I think a cooling shootout is in order.
Arctic introduced its Liquid Freezer II line last year. The Liquid Freezer II 280 earned an Editor's Choice award from our friends at Tom's Hardware, and I can only imagine how much better the new 420 model performs, with a bigger radiator and another fan attached. This is especially enticing as Intel plays fast and loose with power draws in pursuit of higher clocks on its aging 14nm node.
The Liquid Freezer II 420 is compatible with all the modern sockets, among them AM4 for AMD's Ryzen CPUs, and LGA 1200 for Intel's Comet Lake processors (plus others like LGA 115x). It also has sleeved cables, integrated cable management, and a PWM controller pump that Arctic says it developed in-house.
While big in size, the Freezer II 420 is only moderate in price—it costs $140 (€120), which undercuts pricing on some of the best CPU coolers. For example, Corsair's H115i RGB Platinum, our top pick at the moment, is smaller and sells for around $160.