Fractal Design Lumen S24 RGB CPU Cooler Review

Cooling, CPUs, Reviews

Fractal Design shocked reviewers six years ago when its first cooling product outperformed nearly everything in its class. Better still, the Celsius S24’s clean and simple wiring kept it in our test systems, with it radiator-mounted fan hub that made for a one-plug final connection. Those features made Fractal Design the first company we called when it came time for us to do our platform update: Welcome the ARGB-equipped Lumen S24.

Fractal Design Lumen S24 RGB
Thickness28mm (54.5mm w/fans)Connectors(2) 4-Pin PWM (1) 3-Pin Fan, (3) ARGB
Width120mm (4.7″)Weight1134g (40 oz)
Depth273mm (10.75″)Intel Sockets1700, 1200/115x, 2066/2011/1366
Pump Height42.7mm (1.68″)AMD SocketsAM5 through AM2, FM2+ through FM1
Speed ControllerNone (BIOS)Warranty5-Years
Cooling Fans(2) 120 x 25mmWeb Price$130

Unlike our old cooler, the Lumen S24 has been updated to include LGA-1700 compatible brackets. And, desired for its ability to add visual “pop” to a finished system photo, its digitally addressable RGB (ARGB) uses standard (5V 3-pin) ARGB connector to coordinate its color patterns with other ARGB devices.

Putting aside the RGB stuff, a functional difference between the Lumen and Celsius series is that while the Celsius had its pump mounted atop its CPU water block, the Lumen places it inside the radiator, flowing across the center tubes and returning via the side tubes. The alternative design sidesteps a patent that Asetek placed on a technology developed by Sunon for its Waturbo, but the strange thing is that we’ve never seen any evidence of Asetek purchasing Sunon’s patent (Sunon’s Waturbo launched the year before Asetek’s LCLC).

The CPU mating surface is smoothly finished copper with factory-applied thermal compound that Fractal Design supplements with a separate tube of thermal paste, thereby giving its buyers more than one chance to assemble their system. The factory-installed Intel mating bracket slips into a circumferential grove that surrounds the water block, giving it around 240° of support.

Fractal Design provides this handy reference image to aid builders in understanding the AMD and Intel mounting systems:

We slipped the horseshoe-shaped Intel bracket off and the similarly-shaped AMD bracket to complete our AMD socket AM5 installation. Notice that the AMD bracket relies on the motherboard’s original cooler retention hooks, which some users may have misplaced if they’ve ever tried installing a different high-end cooler (click to enlarge).

A few installation notes: First is that the reason we mounted the radiator in this orientation was to keep it as far towards the back of the case as possible, which improves airflow around the voltage regulator heat sinks. Second is that we had to move the pump wire to the other side of the radiator to keep it hidden, which is possible because the radiator frame has two grooves through which the pump wire may be fed. Third is that Fractal Design left the Lumen water block’s ARGB wires exposed, as opposed to the concealed power cable of the Celsius’s water block-mounted pump.

The Lumen S24’s ability to have its water block cap rotated means that we could have rotated the water block beneath without making the logo appear “upside down”. Doing so would have put the coolant fittings on the opposite side and the ARGB wire on top, tucking excess hose length under the block’s bottom and hiding more of the unsightly cable. We simple forget to try this until after we’d already disassembled our system.

System Configuration
CaseThermaltake Ceres 500 TG ARGB
CPUAMD Ryzen 9 7900X: 12 cores/ 24 threads, 64MB L3 Cache
O/C to 5.00 GHz at 1.25 V Core
MotherboardASRock B650E PG Riptide WiFi, BIOS 1.18
RAMSabrent Rocket SB-DR5U-32GX2 64GB DDR5-4800
System DriveHP SSD FX900 M.2 1TB NVMe
Test Configuration
Load SoftwarePrime95 Version 30.8 Torture Test, Small FFTs
H/W MonitoringHWiNFO64 v7.42-5030
SPL MonitoringGalaxy CM-140 SPL Meter: Tested at 1/4 m, corrected to 1 m (-12 dB)

Test Results

This version of Prime95 appears to start out with its most AMD-brutal test first: We wish that it would maintain that exact level of stress through consecutive workloads, but are also happy to leave the system exactly as it is until its replacement. We’ve even gone so far as to air gap it to maintain the load pattern you’re seeing.

CPU and voltage regulator measurements show the powerful Celsius S24 going head to head against Corsair’s same-size H100i under Prime95’s harshest stress. Unfortunately, the Lumen S24 RGB isn’t in the same performance class despite its matched size.

Weaker fans could be the reason for the Lumen S24 RGB’s weaker cooling performance, but we’re happy to see that it’s quieter than its more-powerful competitors.

The Lumen is so much quieter than its competitors that it actually leads our CPU temperature to noise comparison. Maybe it’s not such a weak contender?

The elder Celsius S24 takes the lead in voltage regulator temperature to cooler noise ratio.

Keeping in mind that even our highest voltage regulator temperature was less than 40° over ambient, we’ll point back to the CPU temperature to cooler noise ratio when we say that the Lumen S24 RGB is probably “the better” cooler for someone who doesn’t need the other cooler’s extra capacity. It ran cold enough to keep our monster Ryzen 9 7900X at full throttle throughout our tests, and we’d likely enjoy its quieter behavior in one of our daily-use systems. As to whether it might be a suitable replacement for our updated testing platform, stay tuned!

Fractal Design Lumen S24 RGB
Pros:
Cons:
  • Daisy-chain plugs for easy cable management
  • Low noise
  • Mediocre thermal performance
The Verdict:
Boasting superior noise control and easy installation, the spectacular-looking Lumen S24 beats its Celsius predecessor in the balance…even though it doesn’t cool as well.
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