ARCTIC Liquid Freezer II 420 — High-Performance 420mm AIO CPU Liquid Cooler

Overview

The ARCTIC Liquid Freezer II 420 is an all-in-one CPU liquid cooler built around a 420mm radiator that holds three 140mm fans. It suits builders who want to cool a hot CPU without spinning the fans up.

The catch is that it narrows your choice of cases considerably. In short, it is a strong option if your case supports a 420mm radiator (or you plan to buy one that does) and you don't need lighting.

Its signature feature is a 40mm VRM fan mounted beside the pump. When you switch from an air cooler to an AIO, you lose the airflow the air cooler's fan was pushing over the socket area, and the motherboard's voltage regulators (VRM) tend to run warmer.

This fan is there to make up for that. The fan cables are also routed inside the tubing sleeve, so fewer wires are visible inside the case.

On Amazon.co.Check the retailer's page for the latest user reviews.

With that many reviews and that rating, cooling and noise are unlikely to disappoint. Most complaints come from problems you can catch before buying: the radiator not fitting the case, or the pump interfering with the motherboard.

This article focuses on those checks.

Compatibility Guide

Supported sockets are Intel LGA1700, LGA1200, LGA115x and LGA2066, plus AMD AM5, AM4 and TR4/sTRX4, which covers almost every current platform. The pump and fans connect to the motherboard over 4-pin PWM.

In most builds you plug it into the CPU_FAN (or AIO_PUMP) header.

The case is the biggest hurdle. A case that supports 360mm will not necessarily take a 420mm radiator.

A 360mm radiator is sized for three 120mm fans and a 420mm one for three 140mm fans, so the 420mm unit is both longer and wider. Look for mount-specific entries such as "front 420mm" or "top 420mm" in your case's spec sheet.

If you mount it at the top, check that the radiator plus fans won't hit your RAM or the heatsinks along the top edge of the motherboard. If you mount it at the front, the thickness eats into the space available for your graphics card.

With a long GPU, the most reliable figure is the case's "GPU length with front radiator" spec.

The VRM fan beside the pump also needs room on the motherboard. On boards with tall VRM heatsinks or decorative covers right next to the socket, the pump may collide unless you rotate it.

You can choose the pump's orientation during installation, so check the socket area in photos of your board beforehand.

Threadripper (TR4/sTRX4) is on the supported socket list. However, Threadripper chips have a very large heatspreader.

Being able to mount the cooler and being able to cool the whole heatspreader are two separate questions, so check both, along with the included mounting hardware, on the product page before buying. AM5 is supported because it keeps AM4's cooler mounting scheme.

Product Info

The ARCTIC Liquid Freezer II 420 is a high-end AIO cooler released in 2020.

Note the 200 RPM minimum. At idle or under light work, the fans can slow almost to a standstill, which makes it easy to set up a curve that stays quiet day to day and only ramps up under heavy load.

The 1700 RPM maximum also means the cooler never gets extremely loud, even at full speed.

ARCTIC lists a 6-year warranty. In the box you get Intel/AMD mounting kits, three PWM fans, thermal paste and an installation manual.

When the data was collected on 27 May 2026, the Amazon.co.jp listing was ¥50,603.

That listing came from a parallel-import seller, and prices for this cooler vary widely by seller and over time. Sales and stock also move the price, so check the current price and seller on the product page before buying.

Best Use Cases

• Running a Core i9, Ryzen 9 or similar hot CPU at full load for long stretches: For rendering or video encoding, where full load lasts from tens of minutes to hours, radiator area translates directly into headroom. 420mm is among the largest AIO sizes available.
• Quiet builds that still need strong cooling: Three 140mm fans provide the surface area, so each fan can stay at low speed. The 0.3 Sone noise rating fits that low-speed approach.
• Builders worried about VRM temperatures after switching to an AIO: The 40mm VRM fan makes up for the missing airflow around the socket, which matters when you pair a hot CPU with a board whose power delivery is modest.
• Anyone who wants less visible cabling: The fan cables run along the tubing, so fewer wires need to be routed behind the motherboard tray.

Where It Differs Beyond Cooling

At the same radiator size, AIOs usually land within a few degrees of each other, so the choice often comes down to other factors. This cooler has no LCD screen or RGB lighting.

Instead, it concentrates on practical features: radiator size, the VRM fan and tidy cabling.

So when you compare it with LCD or ARGB AIOs, the question is less about cooling and more about whether you want to pay for lighting and displays. Against a dual-tower air cooler, the deciding factor is whether you accept a pump that can fail and a leak risk that isn't zero.

Before You Buy

Case fit is the biggest hurdle. A 420mm radiator is very large and only a limited range of cases will take it.

The product measures 458 x 68 x 138 mm, and the 38mm radiator is thicker than typical ones. The classic mistake is assuming a 360mm-ready case will do and finding the radiator doesn't fit.

Always confirm 420mm support, and where it can be mounted, in the case's spec sheet.

Watch for motherboard interference. The VRM fan beside the pump can hit the large VRM heatsinks on high-end motherboards.

Crowded smaller boards such as Micro-ATX also leave little clearance around the socket.

There is no lighting. It has no RGB LEDs, so it won't suit builders who want an illuminated interior.

You could swap in lit fans later, but that adds cost and effort. If looks matter, buying an ARGB AIO from the start is more sensible.

It's overkill for low-heat CPUs. A Core i5 or Ryzen 5 used mainly for gaming is often cooled well enough by a mid-range air cooler.

The 420mm size pays off when you load every core for long periods.

Confirm the socket hardware. The cooler launched in 2020, and support for sockets released later was added through mounting kits.

Depending on when your unit was made, the box contents may differ. If you plan to use LGA1700 in particular, confirm with the product page or the seller that the dedicated mounting parts are included.

Price depends heavily on the seller. The listing at collection time came from a parallel-import seller.

Compare it with the domestic retail version, including who handles warranty claims, before you buy.

FAQ

Q. Does it work with AM5 Ryzen 7000/9000 CPUs? A.

AM5 is on the supported socket list. AM5 keeps AM4's cooler mounting scheme, so the AM4 mounts work.

Q. Will it fit a case rated for 360mm radiators? A.

Often not. A 420mm radiator is sized for three 140mm fans and is longer and wider than a 360mm unit.

Check that your case lists 420mm support.

Q. Where do the pump and fans connect? A.

Normally to the motherboard's CPU_FAN (or AIO_PUMP) header over 4-pin PWM. Also check that the header is set to PWM control in the BIOS.

Q. How quiet is it?
A. It is rated at 0.3 Sone, and the fans can drop to 200 RPM, so it is designed to run very quietly at idle.

Q. How long is the warranty? A.

ARCTIC lists 6 years. For parallel-import units the warranty contact may differ, so check with the seller.

Product Disclosure (Amazon)

• Manufacturer: ARCTIC
• Seller: OnlineインポートShop AM支店
• ASIN: B08HLPFXWM
• Note: This article covers a manufacturer-made product based on Amazon listing details.