Arctic Liquid Freezer III Pro 420 Review: Extreme cooling without compromise

Arctic is a name well-known by many PC enthusiasts for often providing high-value, quality cooling solutions. Arctic’s MX-6 is one of the best thermal pastes on the market, and the Liquid Freezer III Pro 360 showed some of the best liquid cooling results we’ve seen when tested on AMD’s Ryzen 9 9950X3D and Intel’s i7-14700K.

Since the release of the Liquid Freezer III Pro, many loyal readers have been requesting that we test the 420mm version of this powerful cooler. And so we’ve tested it with AMD’s Ryzen 9 9950X.

Not to get ahead of our testing, but this cooler will certainly be a strong contender for a spot on our Best AIO Coolers list. It offers industry-leading cooling performance at a very reasonable price. But before we get to testing, let’s look at the cooler’s specs and what’s included in the box.

Cooler specifications

Packing and included contents

Arctic’s Liquid Freezer III Pro 420 arrives in a triangle-shaped box, a very unusual design decision, which certainly makes it stand out. It also certainly makes it harder to ship, but that shouldn’t be an issue for potential buyers.

Included with the product are the following:

• 420mm AIO with pre-installed fans
• MX6 thermal paste
• Mounting for AMD and Intel platforms
• All-in-one or separated PWM cords
• VRM fan

Features of Arctic’s Liquid Freezer III Pro 420

▶️ 38mm thick radiator

This AIO’s radiator is thick. At 38mm for the radiator and 27mm for the fans, that’s a combined thickness of 65mm. This will present compatibility issues with many cases, so make sure to do some measuring before buying. You probably aren’t considering a compact case with a 420mm cooler. Even with our MSI MAG Pano 100R PZ test case, we had to mount the radiator above the top frame, as it doesn’t technically support coolers this large. More on that below in our testing section.

▶️ Anti-bending frame for Intel systems

Intel LGA 1700/1800 CPUs, especially Raptor Lake, have been known to warp or bend in certain conditions. And as a result, the CPU can become harder to cool. This issue can be avoided altogether with the use of a contact frame, which Arctic includes for users of Intel systems. It’s a nice inclusion, but it also complicates the installation process and is a requirement for mounting Artic’s current-gen AIOs on Intel-based systems.

▶️ Low price

Officially, the LF3 Pro 420 carries a MSRP of $148.99, which is a reasonable price in and of itself. However, this AIO is frequently on sale, making it an even better value. At the time of this writing, it is available for only $103 on Amazon.

▶️ MX-6 thermal paste

Arctic includes a small tube of its MX-6 thermal paste. We’ve tested it on both AMD and Intel systems, and it’s one of the best on the market! Check out our thermal paste benchmarks for more detailed information.

▶️ Improved CPU mounting

Different CPUs currently on the market can have different hotspots, which can impact the effectiveness of a cooler. This is why some coolers seem to do better – or worse – with AMD or Intel. Arctic refined its mounting for AMD AM4/AM5 and LGA 1851 systems, resulting in claimed performance increases of up to 9 degrees Celsius with a 250W power limit. We’ll, of course, see how that shakes out shortly, in our testing.

▶️ New P14 Pro Fans – and a VRM fan too!

There’s more to a cooler than just the heatsink or radiator. The bundled fans have a significant impact on cooling and noise levels, as well as how the cooler looks in your case.

The new P12 Pro fans include seven blades instead of the five-bladed fans included with previous Liquid Freezer CPUs, and are pre-installed for convenience. Arctic claims they perform at the same level as its MAX fans, but at a lower noise level. That’s not to say these fans run quietlym though. As you’ll see in our benchmarks below, they can get pretty loud.

A quick connect system for the PWM and ARGB connections is utilized to minimize cable clutter.

AM5 installation

The installation of this cooler is simple, but a bit of a pain for Intel users, due to the required use of a custom contact frame for the CPU. This guide will go over the installation on AMD systems. Intel users can check out our review of the smaller Arctic Liquid Freezer III Pro for installation help.

1. Remove the default AM4/AM5 mounting mechanism.

2. Place the rubber standoffs around the screw holes surrounding the CPU.

3. Take the included mounting bars and place them on top of the standoffs, and then secrure them with a screwdriver and the included screws.

4. Apply the included Arctic MX-6 thermal paste to your CPU. If you aren’t sure how to do this properly, please refer to our handy guide on how to apply thermal paste.

5. Press the pump block on top of the CPU, and secure the built-in screws using a screwdriver.

6. Once complete, connect the cabling to the CPU block’s head. For the purposes of testing, I chose the option with individual PWM control for the fans, pump, and VRM fan. However, some may prefer the simplicity of the all-in-one cable. Connect the cables, place the VRM fan on top of the CPU block, and installation is complete.

Real world testing configuration –AMD AM5 platform

The 9950X3D setup that we started testing coolers with last year has suffered an unfortunate death. As such, we’ve begun to test coolers on a system with AMD’s 9950X.

There are some differences in how the 9950X and 9950X3D CPUs are impacted by thermal events: while the heat output of the CCDs of AMD’s 9950X3D are relatively balanced, the 9950X I’m using has one CCD that runs much hotter than the other, with a difference of over 10 degrees C in some scenarios, shown below.

The benchmark results shared in these reviews may differ from others because I emphasize results that are comparable to real-world use.

This means that I generally test CPU coolers inside of a closed desktop case, which increases cooling difficulty compared to other testing methods. Open benches have lowered ambient temperatures, which in turn makes weak coolers appear stronger than they really are. Some have used generic thermal plates to test cooling solutions. I reject both of these methods, because they don’t accurately reflect the real-world conditions where a CPU cooler is used.

That said, this review bends this rule a little: The MSI Pano 100R PZ case that we use for cooler testing doesn’t technically support 420mm radiators. So I had to place it on top of the case to make it fit. This likely affects thermals and acoustics at least somewhat, but short of re-testing all our coolers in a different case, we didn’t have a better option. We tested Be Quiet’s competing Silent Loop 3 420 in this same way for comparison, while the smaller 360mm coolers were tested in a typical fashion, with the radiator and fans inside the case. If there is heavy interest in large 420mm cooler testing, we will revisit these results in a larger case later this year.