If BMW and Audi were to both introduce a high priced luxury full-sized pickup truck with workman-like capabilities, it may seem a bit of an oddity. If they sold incredibly well, they may well be joined in the ranks with offerings from Lexus and Infiniti. That would put four players in a particular market segment. Strangely, while all four of these companies have extensive experience on the luxury end, their experience is far lighter on the working truck end of the equation. However, there is a luxury car manufacturer with very extensive experience in building commercial trucks, yet we don’t see an offering from them in this scenario. In this instance, Mercedes would be very conspicuous by their absence.




There is a somewhat similar situation in the AiO liquid cooling market. At the onset of its popularity, it was dominated solely by some of the top names in computer components, but companies that had limited commercial products pertaining to CPU cooling prior. The fold was soon joined by companies that were obviously more cooling oriented, but we didn’t see any great shakeups in the market or in performance. NZXT recently joined the fold with the larger 140mm based X40 and X60 models that saw a huge jump in performance capabilities to go along with the larger radiators. It seemed unusual that liquid cooling leader Swiftech and innovative Cooler Master (who has dabbled in liquid cooling in the past) stayed out of the AIO market. However, that is changing and the old pros are entering the field.



Cooler Master’s Seidon 240M boasts an all in-house design and development set to show off all of Cooler Master’s expertise. The Seidon 240M comes equipped with a 240mm radiator, copper contact block and a unique Cooler Master designed pump. The Seidon 240M uses Ultra-Fine Micro Channel technology in their contact plate, which actually increases the amount of water coming into contact with the copper. Simple reason tells you that increased water contact results in greater potential heat dissipation. The Seidon 240M uses kink-free hard plastic corrugated tubing for the liquid path, shown to have better aging and evaporation characteristics than rubber hoses. Two 60-2400rpm 120mm fans capable of over 86 CFM handle the air movement chores for the Seidon 240M, with the wide rpm range offering near silence or extreme performance. The fin design of the 240mm radiator has been tuned to maximize airflow. This results in more efficient cooling, and also considerably cuts down on associated noise.



Unboxing Video Above


Cooler Master Seidon 240M CPU Cooler

Cooler Master Seidon 240M CPU CoolerCooler Master Seidon 240M CPU Cooler



Installation Video Above




Model RL-S24M-24PK-R1
CPU Socket Intel LGA 2011 / 1366 / 1156 / 1155 / 775 

AMD Socket FM1 / AM3+ / AM3 / AM2

Main System Dimension Ø 70 x 27mm (Ø 2.75 x 1.1 inch)
Radiator Dimensions 273 x 120 x 27mm (5.9 x 4.6 x 1.1 inch)
Radiator Material Aluminum
Fan Dimension 120 x 120 x 25 mm (4.7 x 4.7 x 1 in)
Fan Speed 600~2400 RPM (PWM) ± 10%
Fan Airflow 19.17 ~ 86.15 CFM ± 10%
Fan Air Pressure 0.31 ~ 4.16 mm H2O ± 10%
Fan Life Expectancy 40,000 hours
Fan Noise Level (dB-A) 19 ~ 40 dBA
Fan Bearing Type Rifle bearing
Fan Connector 4-Pin
Fan Rated Voltage 12 VDC
Fan Rated Current 0.3A
Fan Power Consumption 3.6W
Pump Life Expectancy 70,000 hrs
Pump Noise Level <25dBA
Pump Connector 3-Pin
Pump Rated Voltage 12 VDC
Pump Load Current 0.15A
Pump Power Consumption 1.8W
Warranty 2 years
UPC Code 884102020049



  • Pre-filled, closed loop liquid cooling system requires zero maintenance.
  • UltraFine Micro Channel cold plate optimizes water flow and heat dissipation.
  • Durable and powerful pump - dissipates heat effectively and maintains temperatures through stable water circulation.
  • Large aluminum radiator with wide RPM range PWM fan creates a superb balance between cooling efficiency and noise.
  • Universal mounting solution supports the latest Intel LGA 2011/1150/1366/1155/1156/775 and AMD FM2/FM1/AM3+/AM3/AM2+/AM2.



To test all heatsinks/fans in this comparison, Hi Tech Legion will maintain an ambient room temperature of 22C. Temperatures will be climate controlled in all instances, so there will be no variance in benchmarks. Noctua NT-H1 Thermal Compound will be used for all comparison units. All heatsinks/fans will be benchmarked in the exact case as its comparisons, unless otherwise specified. HTL does not benchmark heatsinks/fans on a work bench - this is an attempt to show real world statistics. Temperatures will be calculated using either Core Temp or IR Thermometer and will all be measured in Celsius. All load temperatures will be at 100%, achieved by using OCCT, which will be run for 10 minutes before temperatures are measured.

In this review, the $99.95USD retail Cooler Master Seidon 240M CPU Cooler will be tested against the following comparison units. The units were tested in succession in the same build, and only results from these tests were used.

  • Phanteks PH-TC14PE - $84.95 retail
  • NZXT Kraken X40 - $99.95 retail
  • Corsair H100 - $119.95 retail


Test System:


System Specifications

  • Processor: Intel Core i5 3570K, 3.4GHz Stock and 4.6GHz OC
  • Motherboard: ASUS Z77 Sabertooth
  • Video Card: Gigabyte GTX 660 Ti OC
  • Memory: 8GB ADATA XPG Xtreme DDR3-2133
  • Case: Fractal Design Define R4
  • Power Supply: EVGA SuperNova NEX 1500W
  • Hard Drive: Corsair Neutron GTX 120GB/Western Digital Caviar Black 750GB
  • Media: LG BluRay Combo Drive
  • Operating System: Windows 7 Ultimate 64
  • Thermal Paste: Noctua NT-H1




  • OCCT x 10 minutes for Load Temperatures



Cooler Master Seidon 240M Benchmark

Cooler Master Seidon 240M Benchmark

We first tested the Seidon 240M on the Core i5 3570K at its default 3.4Ghz. Next, we were able to achieve a stable overclock of 4.6Ghz @ 1.34Vwith temperatures staying within the processor specs.



Provided by: Cooler Master

No compensation was received for review of this product.

Price Point

Price: $99.99 USD Retail

Class: Enthusiast

The Cooler Master Seidon 240M CPU Cooler is in the Enthusiast class of CPU coolers.


The Seidon 240M delivered excellent cooling performance under all conditions, the best we have seen from an AIO 240mm solution to date. The 240M also delivered the lowest noise levels of any of the 240mm units we have seen, delivering moderately quiet performance in day-to-day usage.

Reviewer's Opinion

I was always surprised that Cooler Master was not in the AIO Liquid Cooling market earlier, but by the same token, I was quite happy that they did not jump into the “me too” category of retreading the same OEM pieces that we have seen before. In Cooler Master fashion, they took their own route and came out with something decidedly different. While different is not always a good thing, in the case of the Seidon 240M, it is a very good thing.

One glance at the Seidon 240M lets you know that you are not looking at a cooler you have seen before. The pump and cooling block unit is an entirely different design than what we have seen previously. It is squatter, with more efficient side inlet/outlet placement and a very large copper contact plate. Cooler Master contends that the design is entirely their own, and I would not argue the point. It is sleek, well-engineered and obviously effective. An added bonus is the control software, or in this case, lack of. You can control the fans entirely with your BIOS/software, and set it up exactly how you like it in your system, and tweak all you like. It is a simple, effective, flexible solution.

Cooler Master makes quite a point of showing off the Ultrafine Microchannel design of the contact plate, and the theory certainly pays off in practice. The performance of the Seidon 240M was excellent all around, handling the high overclocks with ease, and easily bettering the more expensive 240mm units we have seen previously. Aside from the outstanding peak temperatures, the Seidon 240M also showed very quick cool down times with decreasing loads. There is no doubt that the Seidon 240M does an excellent job of dissipating heat on all ends, from the cooling block to the radiator.

Over time, the only complaint I have ever had with Cooler Master has been fan noise, so I was expecting the worst, given that 240mm AIOs tend to be the noisiest cooling solution imaginable. However, I was very nicely surprised when the Seidon 240M turned out to be the quietest 240mm solution I have heard to date. Make no mistake, when the fans are going full speed, the Seidon 240M is loud, but not the earsplitting volume we have seen from Corsair, the Tt Extreme and Antec 920 (not a 240mm, but the loudest of the bunch). After doing a little tuning of my fan control, in day to day activities, the Seidon 240M remained very tolerable, and around the middle of the pack from any type cooling solution. Even under heavy loads, the noise levels of the Seidon 240M were within expected limits. The great dissipation of the unit definitely helps in keeping the fan speeds and noise levels down, and makes the Seidon 240M a great 24/7 cooler.

The real kicker on the Cooler Master Seidon 240M is the price point; $99.95 MSRP. So, you get better cooling performance, less noise, easy installation and setup, and top notch build quality for less than what we have been seeing. There has to be a downside, right? Well, if there is, I can’t find it. Cooler Master may have been late to releasing their AIO, but they are still the old pros in cooling and the Seidon 240M showcases their experience and innovation. With all of this going for it, can we possibly give the Cooler Master Seidon 240M anything but our highest award?



  • Excellent Cooling at Idle and Full Load
  • Very Reasonable Noise for a 240mm Rad/Dual 120mm Fan
  • Excellent Cooling at Low Fan Speeds
  • Price Point Lower Than Direct Competition
  • Very Easy Installation In Cases With Proper Room
  • Easy to Work With Kink-Free Tubing
  • Maintenance Free
  • Unique Pump Design
  • Excellent Build Quality and Finish
  • Micro Channel Block Design
  • Pump Near Silent
  • High Overclock Easily Achieved While Keeping Well Within Thermal Limits



  • Loud At High Fan Speeds


Hi Tech Legion Editor’s Choice Award