Silence is golden: Fractal Design’s Celsius+ S28 Prisma 280mm AIO Liquid Cooler Review

Edited 3/16: Clarified wording about the silent mode and how I evaluate Ryzen 7700x cooler performance at the default TDP

Swedish company Fractal Design is well known amongst PC enthusiasts, their recently released North computer case has been received well by the public and reviewers. I recently reviewed Fractal’s Celsius+ S36 Prisma (360mm) for Tom’s Hardware, pairing it with Intel’s i9-13900K, and it was one of the best coolers I’ve had the pleasure of testing. Today we’ll be testing the 280mm version of the Celsius+ lineup. Last month I showed the results of this cooler with Ryzen 7700X on AdoredTV – this review will have those results with additional comparison coolers as well as testing with Intel’s i9-13900K.

Packaging and Included Contents

Like most other AIOs on the market, Fractal’s Celsius+ S28 arrives in a box that has molded cardboard to carefully fit and protect the contents during shipping. The contents are also protected with plastic coverings.

The Celsius+ S28 comes:

  • User Guide
The inner packaging of the Celsius+ S28 and the inner contents
  • 280mm Radiator & CPU Block
  • 2x 140mm fans
  • Mounting for modern AMD & Intel platforms

Cooler Installation

The installation of the Celsius+ S28 Prisma is simple and easy. Normally I would show my own installation photos here, but Fractal Design created a quick 48-second YouTube showing the full installation process on AM4/AM5 systems which I feel is much better than any photo could do. It’s linked below.

The main difference that occurs when you’re installing the cooler on an Intel system is that you’ll use a backplate and screw the standoffs into that backplate.

Source: User Manual

Features of Fractal Design’s Celsius+ S28 Prisma

RAM ClearanceAll heights supported
Thermal CompoundPre-applied
Fin & Housing MaterialAluminum
Pump Bearing TypeCeramic bearing and shaft
Pump Speed800-2800 RPM in normal use, 3500 RPM during thermal protection mode that activates if liquid temperature is over 60°C
Pump Noise20 dBA
Radiator Dimensions143 x 30 x 324 mm
Compatible SocketIntel LGA 1700, 1200, 1150, 1151, 1155, 1156, 1366, 2011, 2011-3, 2066
AMD AM2, AM2+, AM3, AM3+, AM4, AM5, FM1, FM2, FM2+
Manufacturer Warranty5 Years

PWM and Auto (Silent) Modes

Arctic’s Celsius+ coolers can switch between silent mode and PWM mode with the flick of a wrist. The Auto (Silent) mode impressed me when I tested the Celsius+ S36 for Tom’s Hardware (the 360mm version of this cooler), I found that the silent mode offered total cooling capacity equal to the highest end air coolers while remaining perfectly quiet.

Full Copper CPU plate with pre-applied thermal paste

30mm Radiator with Built-in PWM & ARGB hub

The included radiator measured 30mm, just slightly thicker than most radiators on the market today. This should fit most cases, but might cause issues in the most space constrained of cases. Fractal Design’s Celsius+ S28 Prisma was designed to enable a clutter free installation, and includes a PWM & aRGB header hub to this end.

140mm Fractal Design Prisma AL-14 PWM Fans

There’s more to a cooler than just it’s heat sink, the fans paired with a cooler have a huge impact both total cooling potential and noise levels – included with the Celsius+ S28 Prisma are 2x Prisma AL-14 PWM 140mm Fans.

Model Prisma AL-14 PWM ARGB
Size140 x 140 x 25 mm
SpeedPrisma AL-14 PWM ARGB
AirflowUp to 103.9 CFM/176.44 m3/h
Static PressureUp to 2.38 mm H2O
Noise LevelUp to 34.1 dBA
BearingLong Life Sleeve (LLS)
Low (0-20%) PWM speed500 RPM
Low PWM noise level15.1 dB(A)
Low PWM airflow31.67 CFM
Low PWM static pressure0.44 mmH2O
Connector4-pin PWM
Rated LifespanOver 100,000 hours

System Configurations Tested

AMD Ryzen 7000 Raphael Platform:

CPUAMD Ryzen 7 7700X
MotherboardASRock B650E Taichi (sampled by ASRock)
Computer CaseDeepCool CK560WH (sampled by DeepCool)
Storage1TB Kingston Fury Renegade
GPUIntel ARC A770 LE (sampled by Intel)
RAM32GB (16gb x2) Crucial DDR5-4800 (Sampled by Micron)
Coolers Tested(Click the links for previous reviews)
BeQuiet! Pure Rock LP
Iceberg Thermal IceSLEET G4 Silent
Fractal Celsius+ S28

Intel 13th Generation Raptor Lake Platform

CPUIntel i9-13900K (sampled by Intel)
MotherboardASUS Z690 PLUS WIFI D5
Computer CaseCooler Master HAF 700 Berserker, system fans set to 35% (sampled by Cooler Master)
Storage1TB Micron P3 Plus, 1TB Micron P3
GPUIntel ARC A770 LE
RAM32GB (16gb x2) Crucial DDR5-4800
Coolers Tested
(See Tom’s Hardware for more comparison data)
(Click the links for previous reviews)
BeQuiet! Pure Loop 2 FX
CoolerMaster PL360 Flux
DeepCool LT520
Enermax AquaFusion ADV
Icebert Thermal IceSLEET G4 Silent
Thermalright Frozen Notte 360

AMD Ryzen 7 7700X Thermal & Acoustic Results

I’ve had a limited amount of time to test coolers on Ryzen 7700X, as such my results here will be limited. As I continue to test coolers on AMD’s platform, this data will grow.

Default (105W) PPT

At the default PPT of 105W, the most intensive loads can be difficult to cool and often result in the CPU running at TJMax. As such, we’ll be looking at two metrics in this situation: noise levels and total watts dissipated by the cooler.

Some of y’all might notice that the graph starts at 36 instead of zero – this is because my sound meter cannot measure noise levels lower than 36 dBA, effectively making it the noise floor for our testing purposes.

In PWM mode at full speed the AL-14 fans can bring noise levels up to 48.5 dBA. This isn’t quiet, but it isn’t loud either. In Auto mode – or as I prefer to call it: Silent Mode – the total system noise levels were supremely quiet, measuring at 36.4 dBA – which is basically as low as I can reliably measure. It’s quite possible that the noise levels are truly lower, and that my sound meter is incapable of properly measuring it’s noise output.

In situations where the CPU hits TJMax, the best way to compare cooling performance is to measure the total amounts of watts consumed by the CPU. We can see from the results above that higher end cooling solutions will have limited returns when paired with AMD’s Ryzen 7 7700X. Fractal’s Celsius+ S28 was only able to cool 17W more (a 14.7% increase) than IceBerg Thermal’s entry-level IceSLEET G4 Silent in this scenario.

How well does that 14.7% higher power consumption while using stronger cooling translate into improved performance? Not very much at all. At 19298 vs 18774 points in Cinebench R23, we’re looking at 2.7% total increase in performance overall. This is a much smaller gap than I would have expected from Intel’s i9-13900K, where I’ve seen a 6% drop in performance using basic air cooling.

In this authors opinion, where Fractal’s AIO shines is in it’s Auto (Silent) mode. While technically it cools a few watts shy of Iceberg Thermal’s entry level air cooler in this mode, it does so while running completely silently.

95W CPU Power Limit

Imposing even a minor power consumption limit on AMD’s Ryzen 7700X reduces cooling difficulty dramatically resulting in the ability to easily to cool the CPU under TJMax (95c), as such in these situations the total noise levels are more important. It’s also important to test in these TDP restricted situations, because most “real life” workloads will not push the CPU to it’s limits.

The advantage of liquid cooling shows in the acoustic results of this wattage limited test. In both the Auto Mode which is designed for complete silence AND the PWM mode in which the motherboard aims to maintain a lower CPU temperature, Fractal Design’s S28 Prisma runs quieter than IceBerg Thermal’s G4 Silent – an air cooler also designed for low noise levels!

75W CPU Power Limit

Lowering the PPT to 75W further reduces the cooling difficulty, bringing temperatures down to 40.9C over ambient in PWM mode and 50C over ambient in Auto (Silent) mode. Total system noise level is very quiet in the PWM mode, but at 38.2 was curiously just as loud as in the 95W mode.

Thermal results in this scenario are interesting, with the Celsius+ S28 in PWM mode maintaining an 8 degree lead over comparison air cooler. In comparison to EKWB’s push-pull AIO, the Celsius+ S28 runs 2C warmer – but EK’s AIO runs much louder in this scenario.

Intel i9-13900K Thermal & Acoustic Results

No Power Limits

Moving over to Intel’s i9-13900K, let’s look at the maximum wattage results – these results only have a limited amount of information, but I’ve published more comparative information on Tom’s Hardware, which is shown below. These results are directly comparable because they were performed using the same system, by the same person (me!).

Source: Tom’s Hardware

The results here are looking good for Fractal. Measuring 290.8 watts cooled, it’s performance here is similar to many 360mm coolers on the market – and in PWM mode it’s only 5W behind it’s bigger brother, the 360mm Celsius+ S36 Prisma.

Switching the cooler to the silent mode reduces cooling capacity to 252W – which is still plenty strong enough with Intel’s i9-13900K and matches Intel’s recommended PL2 limit. You won’t gain much performance by letting the CPU consume more power.

Looking at the acoustic performance, Fractal’s Cooler aligns almost perfectly with the average noise level recorded amongst all coolers I’ve tested with this system. Those who prefer quiet operation will love the silent mode, as it runs so softly that my system fans overpower the sound of the cooler.

Source: Tom’s Hardware

200W Thermal & Acoustic Results

Most loads that common users run won’t use more than 200W, so this is a better analogue for what folks will see in day to day usage. At 53C, the results here are in line with most other AIOs on the market. While this thermal performance is merely on par with the competition – the noise it creates while achieving that thermal result is not! Fractal’s S28 ran quieter than every cooler I’ve ever tested in this scenario except for one model!

Check out my articles at Tom’s Hardware for more comparison results.

125W Thermal & Acoustic Results

When restricted to 125W, thermal performance really isn’t a concern – though I’ve included that information in the graph below. Really, any cooler should be able to handle this load – even Intel’s stock cooler! Acoustic performance is much more important here, and Fractal Design’s S28 ties here for the quietest result I’ve recorded in this scenario.


Fractal Design’s Celsius+ S28 AIO is one of the best coolers I’ve had the pleasure of testing. In it’s completely silent mode, which runs quieter than my noise meter can properly record, it still handles over 250W with Intel’s i9-13900K. In it’s PWM mode, it’s capable of handling over 290W.

Even in PWM mode, you’ll only notice the sound of the cooler in the most intensive loads – virtually all common loads run whisper silent. If this cooler interests you, it can currently be found for $149.99 USD on Amazon

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