be quiet! Silent Loop 3 420 AIO CPU Cooler Review

1. be quiet! Silent Loop 3 4202. Test Results3. Closing Thoughts4. View All Pages

With CPU package power on an upward trajectory, we are seeing more 420mm AIO coolers hit the market. The latest AIO unit we have for review is the Silent Loop 3 420 from be quiet! It’s the company's first 420mm AIO, featuring a 3-chamber pump design, a high-density cold plate fin stack, and an easy-access filling port. It's also equipped with be quiet!'s premium Silent Wings 4 PWM fans and ARGB lighting. be quiet! says that all this combined will produce low noise, high performance cooling, so let's dive straight into this review and find out if that’s true.

Timestamps:

00:00 Start
00:50 Details / Pricing
02:12 Up close
04:30 CPU Block and Radiator
05:24 Fans
06:54 Accessories and mounts
07:51 AMD Test System / Installation
09:58 Test Results
11:52 Closing Thoughts

Features:

• According to be quiet! the Silent Loop 3 offers high performance cooling for modern CPUs with its powerful 3 chamber pump, large area high density cold plate fin stack and Silent Wings 4 PWM high speed fans.
• It features a premium yet elegant design with discreet ARGB CPU block lighting, it's available in 420, 360 and 240mm sizes and includes support for all current desktop sockets including an AMD Threadripper mounting frame with 360 and 420mm units.
• As always with be quiet! AIO coolers, the Silent Loop 3 is equipped with an easy to access refill port for when maintenance is due, and it comes with a 3-year warranty for peace of mind.

Specifications:

• CPU Socket Compatibility: Intel 1851/1700/1200/115X, AMD AM5 / AM4 / TR5 / TR4
• Radiator Material: Aluminium / black spray painted
• Radiator Dimensions: 457 x 140 x 27
• Radiator Tube Length: 400mm
• CPU Block Dimensions (H x W x D): 5 x 80 x 56 (mm)
• Pump Speed: 1700 – 3500 RPM
• Cold Plate: Copper/nickel plating
• Pump Connector: 4-pin PWM
• LCD Screen: N/A
• Pump Noise: N/A
• Pump LED: 3-pin 5v ARGB
• VRM Fan: N/A
• Fan Dimensions: 140 x 140 x 25 mm
• Fan LED: N/A
• Fan Speed (PWM): 1900 RPM (Max)
• Fan Max Airflow: 78.4 CFM
• Fan Max Air Pressure: 2.36 mmH2O
• Noise (dBA) at 50% / 75% /100% rpm: 19.4 / 29.3 / 34.3
• Fan Bearing: FDB
• Fan Connector: 4-pin PWM
• Warranty: 3 Years

Test System Specifications:

• CPU – AMD Ryzen 9 9950X
• Motherboard – ASRock Phantom Gaming X870E Nova WiFi
• Memory: 32GB (2 x 16GB Modules) Kingston Fury DDR5-6000
• Graphics card: MSI Radeon RX 6600 XT Gaming X
• Storage: 1TB Corsair MP600 Elite PCIe Gen4x4 NVME M.2 SSD
• Power Supply: Seasonic Prime TX-1000
• Chassis: Open Test Bench
• Thermal Compound: Arctic MX-6
• O/S: Windows 11 Version 24H2

Testing Methodology:

We are primarily focussing on the performance of each cooler at 100% fan speed and also when locked to 40dBA noise output. We will focus on cooling performance using a manual overclock with all-core frequency and VCORE locked to 5.2GHz/1.3v (AMD) and 5.5GHz/1.3v (Intel) and Precision Boost Overdrive performance.

• The test data is logged using HWINFO and the final 10 minutes of the data is calculated to find the average CPU temperature and CPU clock multiplier (AMD PBO Test) and then plotted in the charts.
• For testing, we use a 30-minute looped run of Cinebench R23 and record the steady-state CPU temperature at the end of the test. This ensures that the CPU has had ample time to warm up and reach a steady state under all of the coolers.
• The ambient is maintained at 19-21 degrees Celsius. Where there is variation beyond this temperature range, we add extra repeated tests to ensure consistency. However, this is well controlled now with A/C.
• We also test each cooler with at least two fresh installs (typically three) to mitigate the likelihood of poor mounting spoiling results.
• Ambient temperature and humidity are controlled via a mini split air conditioning system inside the test room. Ambient temperature is maintained between 19-20C, Temperature delta figures are shown in the charts (ambient temperature is deducted from the measured component temperature).

Test Results:

Acoustics

We’ll start by looking at noise output as this will give us a good indication of performance based on noise.

With a 100% PWM speed of almost 1900 RPM , the three 140mm be quiet! Silent Wings 4 fans output just 45dBA noise which makes the Silent Loop 3 420 one of the quietest coolers to be tested on our new AMD Ryzen 9 9950X system, which is impressive since large fans running at high RPM are usually much louder.

Thermal Performance: AMD Ryzen 9 9950X

With the fans running at maximum speed at around 1900 RPM, the be quiet! Silent Loop 3 420 shows decent thermal performance at 60°C average over ambient. However, it only matches the performance of its smaller and older sibling, the be quiet! Light Loop 360. But performance is within a couple of degrees of the Silverstone Ice Myst 420 and Corsair H170i RGB, however there's a clear gap to the best in the chart.

Restricting all coolers to 40dBA noise limit puts everything on a level playing field and the true performance can be measured.

The Silent Loop 3 420 holds on to performance with fan speed reduced, but it still only matches the Light Loop 360. It’s a couple of degrees better than the Corsair H170i RGB but the Silverstone IcyMyst 420 pulls a few degrees cooler at 40dBA so the Sight Loop 3 performance is a little disappointing as it’s the newer of the 420mm AIOs in our data pool.

Most AMD users will likely be running their CPUs with dynamic clock frequencies, so we run the full fan speed test again with AMD Precision Boost Overdrive enabled in the motherboard BIOS and measure the performance.

In this scenario the be quiet! Silent Loop 3 again does ok with an average clock multiplier of 52.5x at 70°C over ambient, which is a minor improvement over the 420mm Corsair unit but as we saw in the other thermal tests, it's not blistering performance and only on par with other 360mm units.

The be quiet! Silent Loop 3 420 is a bit of a mixed bag. On the one hand you get a nice blend of quiet operation – even at maximum fan speed – and subtle looks with a hint of ARGB lighting. But on the other hand, for its huge radiator size and triple 140mm fans, it's not producing blistering thermal performance. In fact it's only on par with its smaller and older sibling, the be quiet! Light Loop 360. Some 360mm units from other vendors are even ahead in terms of thermal performance, especially when looking at the 40 dBA noise normalised data.

Don’t get me wrong, the thermal performance is OK, there's no sign of our AMD Ryzen 9 9950X CPU thermal throttling or anything like that… but it's only OK, and I would expect a brand new 420mm AIO to perform a little better. The noise output is quite impressive though, even with three 140mm fans running at 1900RPM the cooler only outputs 45dBA which is excellent for this size cooler with fans running at high speed.

Build quality seems fine, the satin finish coating on the radiator looks smooth, tubing length is good at around 400mm, the rubber tubing is flexible and covered with a high quality braided sleeving. Installation is also pretty simple and all power and RGB connections use standard 4-pin PWM and 3-pin 5V ARGB so they can connect directly to motherboard headers, with no need for additional control hubs or software.

420mm and 360mm versions of the Silent Loop 3 also support high-end desktop AMD Ryzen Threadripper CPUs, which is a bonus. The ARGB lighting effects look nice and bright and the LEDs diffusion is good. However the warranty is a little poor, only 3 years is offered by be quiet! compared with the competition – including some much cheaper units – offering up to 6 years. But the price seems reasonably competitive for a 420mm unit at £125 in the UK.

the be quiet! Silent Loop 3 420 is available to purchase from Scan priced at £124.99 HERE.

Pros:

• Quiet even at high fan speed.
• Subtle looks should fit any system style.
• Easy to install and setup – no hubs or software required to work.

Cons:

• Only middling performance for the size.
• 420mm radiator won't fit all ATX cases.
• Wiring can be tricky to manage – daisy chained or interlinked fans would help.

KitGuru says: If low noise is what you look for in an AIO then the be quiet! Silent Loop 3 might be ideal for you, but you are losing thermal performance versus some of the competition.

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