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Cooler Master > 
Item#: 9SIA6J33291639

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  • Overview
  • Specifications
  • Warranty & Returns
  • Reviews

Cooler Master Seidon 120M Liquid CPU Cooler

The Seidon 120M is Cooler Master’s latest, incredibly compact watercooling kit that aims to bring watercooling to the masses. It fits in virtually every case, is compatible with every available Intel and AMD platform, and as easy to install as a heatsink. It comes factory filled, sealed and tested with a two year zero maintenance guarantee. Thanks to a 120mm PWM fan with a wide RPM range Seidon can operate silently or unleash a powerful cooling storm at your command.

Utilizes a micro-channel design to maximize surface contact area to quickly pull heat away from your processor.
A reassuring blue LED indicator light shines brightly when the pump is powered and running properly.
Supports the latest sockets from Intel and AMD

- Intel LGA 2011/1366/1156/1155/1150/775

- AMD Socket FM2/FM1/AM3+/AM3/AM2
Guaranteed for maintenance-free operation for years to come without the need to refill coolant.

Technical Specs:

Model RL-S12M-24PK-R1
CPU Socket Intel LGA 2011 / 1366 / 1156 / 1155 / 1150 / 775

AMD Socket FM1 / AM3+ / AM3 / AM2
Main System Dimension Ø 70 x 27mm (Ø 2.75 x 1.1 inch)
Radiator Dimensions 150.3 x 118 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 17dBA
Pump Connector 3-Pin
Pump Rated Voltage 12 VDC
Pump Load Current 0.15A
Pump Power Consumption 1.8W
Warranty 2 years
UPC Code 884102018930


  • newegg Superior cooling performance The COOLER MASTER RL-S12M-24PK-R1 features a waterblock machined out of a single block of copper for the best possible heat transfer. Precision machined Micro Channels maximize the water contact surface to quickly dissipate heat. Plus, its compact 120mm aluminum radiator fits in virtually any case, internal or external to satisfy various needs.
  • newegg Speed control for low noise Fin design is optimized for minimum air restriction to reduce fan speed and noise. 120mm PWM fan with a wide RPM range fines tune and balances fan noise and performance.

Learn more about the Cooler Master RL-S12M-24PK-R2

Warranty, Returns, And Additional Information

Customer Reviews of the Cooler Master RL-S12M-24PK-R2

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  • Anonymous
  • 2/7/2016 9:47:42 AM
  • Ownership: 1 month to 1 year
  • Verified Owner

5 out of 5 eggsGood Cooler

Pros: No problems
Keeps the CPU really cool

Cons: Kind of loud

Did you find this review helpful? Yes No

  • Jonathan D.
  • 1/25/2016 1:44:18 PM
  • Ownership: 1 month to 1 year
  • Verified Owner

1 out of 5 eggsFirst liquid cool

Pros: Good and cool easy install

Cons: -Bought 9-21-15 and as of right now I am on my laptop and I have greenish colored coolant from the cooler all over my graphics card. Luckily I noticed my fan speeds were going higher than normal so HOPEFULLY nothing in my system is fragged. Starting the process to attempt to get this fixed or resolved will update as process continues. NOT HAPPY AT ALL with quality as it is LEAKING all over my gpahics card and motherboard. Would give 0 eggs but it wont let me.

Other Thoughts: UPDATE If customer service and a quality product is what you are looking for do not buy from Cooler Master. 11 Days after they notified me they received the defective product I finally called them. They inform me they do NOT have any coolers to send me and want to refund my money. When asked why they hadn't contacted me they gave me the old "we were just calling" line. Basically I feel they lied 2 times at least in this one call. To say you have NO cooler products and then they were "just getting to calling me". IMO They had me waste my 15 bucks shipping it to them and decided its better business to just refund than to pay to ship me a new product. Needless to say I will NEVER buy another cooler master product and suggest heavily the same to my friends. From shipping time to them until now has been almost 3 weeks and now I have to find and order a new cooler pay shipping on that also and the time it takes to get it here. So not only will my computer be down for total about a MONTH it will actually cost me prob an extra 30 bucks in just shipping alone due to their low quality product and what they call "customer service".

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  • Christian H.
  • 1/14/2016 1:43:53 PM
  • Ownership: 1 week to 1 month
  • Verified Owner

5 out of 5 eggsGreat Value, cool & quiet.

Pros: -Easy installation
-Extremely quiet operation
-Excellent cooling, my i5-6600k idles around 15c and 28c while gaming

Cons: -Hoses are a little stiff, just consider where you're going to mount the rad and which way it will be facing before bolting things in place as you may need to flip it around to get the hoses to good place.
-Mine came with a couple of the fins bent slightly on the radiator, didn't imagine it would affect the cooling very much so it wasn't worth trying to RMA the product. So far the cooling doesn't seem to be impacted.

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  • marco r.
  • 12/29/2015 9:48:16 PM
  • Ownership: 1 month to 1 year
  • Verified Owner

5 out of 5 eggsGreat Product

Pros: Easy to install, no need to worry about checking the water lvl (at least for a couple of years). It also gives it a nice look inside my computer case.

Cons: I can't find any real answer on how long these type of AIO coolers go for before needing replacement or refill.

Other Thoughts: AIO water coolers are nice for first timers who want to dip their toes into water cooling. I expect this cooler to last me at least a few years so I'll be saving to buy a real custom water cooling kit.

Did you find this review helpful? Yes No

  • kane s.
  • 12/13/2015 8:51:36 AM
  • Ownership: 1 day to 1 week
  • Verified Owner

5 out of 5 eggsGreat Cooler

Pros: Install is a breeze and keeps your cpu ice cold.

Cons: The mounting screws for the radiator are too short. Not enough to knock an egg off over, but it should be really nice if they were longer to ensure a truly proper mount.

Did you find this review helpful? Yes No

  • jose l.
  • 12/3/2015 9:20:34 AM
  • Ownership: 1 month to 1 year
  • Verified Owner

2 out of 5 eggsissue

Pros: it's small for a small type case

Cons: the main issue is that the pump stop working in few months my die few days ago don't buy it

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  • Anonymous
  • 12/2/2015 1:19:03 PM
  • Ownership: 1 month to 1 year

5 out of 5 eggsPrice for performance

Pros: Nearly silent
Great price
Great cooling

Cons: none so far

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  • Anonymous
  • 11/24/2015 7:40:52 AM
  • Ownership: 1 week to 1 month
  • Verified Owner

1 out of 5 eggsBad Pump and Dented radiator

Pros: Looks good, easy installation.

Cons: Bought this cpu cooler a few weeks ago. Installation was easy enough but the mounting screws did not come in the package. As of last week I started to use it. Under heavy use the pump started clicking and died in 2 days.

Manufacturer Response:

We apologize for the trouble you are having with the Seidon 240M

Please contact us through CM Fanzone so we can get you a replacement.

CMUSA Support

Did you find this review helpful? Yes No

  • Ursus U.
  • 11/12/2015 3:38:34 PM
  • Ownership: 1 month to 1 year
  • Verified Owner

5 out of 5 eggsMy PC is at idle temps all the time

Pros: This keeps my processor at just above room temperature all the time. When I stress the processor the temps go up to around 40 at the max and then they immediately go down back to idle temps. Can't get any better than that.

Cons: The fans are loud when they're at more than 75%. I set my fan curve so they only get here under stress. They're not loud enough to hear while wearing head phones though

Other Thoughts: No fancy software to get in the way. I like to control it from the bios and it just works. This model is cheaper than some competitors but there isn't any room for an all in one cpu cooler to be better than this. I might replace the fans to be quieter one day when I get more into gaming. Until then, this product fits my needs perfectly as is.

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  • Anonymous
  • 11/5/2015 10:42:57 AM
  • Ownership: 1 week to 1 month
  • Verified Owner

5 out of 5 eggsExcellent cooler for i7-4790K 4 GHz

Pros: This cooler installed easily and does its job. It keeps my i7-4790K 4 GHz (88 TDP) processor around 43 degrees Celsius during full load and around 35 when the PC is idle. Well within normal operating temps.

Cons: None.

Other Thoughts: I would not hesitate to purchase this in the future for my next build.

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Home > 
Components > 
Fans & PC Cooling > 
Water / Liquid Cooling > 
Cooler Master > 
Item#: 9SIA6J33291639
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