Cooler Master Seidon 120M review

Cooler Master is no stranger to all-in-one liquid cooling solutions, and after all their Aquagate products took the South African hardware community by storm in 2009, every second gamer has been wanting a piece of the water-cooling action. Fast forward a couple of years, and companies such as Antec and Corsair are dominating the all-in-one liquid cooling market. Cooler Master hasn’t been idle though, and have a new water cooling system to try and reclaim the top spot, the Seidon 120M.


The main feature of the Seidon 120M is the all-in-one maintenance-free approach. All the elements of the water cooling loop are enclosed into a sealed unit, which eliminates the risk of leaks due to improper installation, and negates the need for refilling the loop. Like other water-cooling solutions of its kind, the Seidon 120M can be installed by a user who has not dealt with water-cooling before, and once installed, requires no more attention than a basic air-cooler.

Another standout feature of the Seidon 120M is the installation compatibility with every Intel and AMD platform available today. This includes LGA 2011, LGA 1366, LGA 1156, LGA 1155 and LGA 775, as well as FM1, AM3+, AM3 and AM2. The mounting options are also self explanatory to seasoned hardware installers, though there are easy to understand for the less experienced.

The Seidon 120M also features a low profile block/pump to fit smoothly into any case. The fan and radiator are also on the thin side – a major plus if the user wants to install the Seidon 120M into an HTPC or case with very little room to spare.

Cooler Master Seidon 120M front

Cooler Master Seidon 120M front

The cooling unit is bundled with a single PWM fan (600rpm to 2,400rpm), however, there are mounting screws and holes on the radiator for an additional 120mm fan to be set up in a push pull configuration. A push pull configuration is where two fans are installed on either side of the radiator. One is set up to push air through, while the other on the opposite side pulls the air. This usually results in a higher amount of flow through the radiator, improving cooling performance. The setup also comes with Cooler Master branded thermal paste for the CPU, allowing for multiple applications rather than just a single application if the thermal compound was pre-installed on the cooling block.

Previous Cooler Master all-in-one coolers used rubber hoses which are easier to bend and maneuver around a case. However, according to a Cooler Master rep, the evaporation loss of liquid with rubber hoses is too high. “Rubber hoses we’ve tested have too high evaporation loss, we know because we used them in 2009 with the Aquagate Viva, and the original R120 all in one cooler,” according to a Cooler Master vendor rep on the Forums. “We’ve tested our ‘plastic’ hoses to have far more resistance to evaporative liquid loss,” he continued.

These new plastic hoses are slightly stiffer than the previous rubber ones; however we had no problem installing the Seidon and were happy with the plastic hoses.

In use

Installing the Seidon 120M took less than 5 minutes on an Intel LGA 1155 platform and was one of the easier units we’ve installed. Connecting the radiator to the chassis was also a breeze, with the plastic hoses bending easy enough not to become an issue.

Cooler Master Seidon 120M installed

Cooler Master Seidon 120M installed

The hoses are also long enough for the unit to be installed in large cases such as the Cooler Master ATCS 840 without being too long and getting in the way. Tightening the mounting screws on the CPU block was easy enough, and they give plenty of feedback so you’ll know when they’re in place. This helps with avoiding mounts that are too tight or too lose (both of which will result in sub-par performance).

The bundled thermal paste is not the best we’ve ever worked with, but is good enough to do the job. Cooler Master provides ample amounts of the paste for multiple installations – be careful not to use too much though, as this will result in poor cooling performance. A pea-sized drop of paste is enough for larger CPUs and you can get away with slightly less on smaller ones (Socket LGA 775 chips for example). The paste spreads well after the cooler is installed and run in for short period, and offers decent cooling performance.


Our test rig consisted of the following:

  • Intel Core i5 Ivy Bridge
  • Asus Maximus V Formula
  • 2 x 2GB Transcend aXeRam DDR3 2000MHZ
  • Gainward Nvidia GTX 570
  • G.Skill 60GB Falcon Pro SSD drive
  • Cooler Master ATCS 840

For idle tests, we allowed the system to boot up and sit at the windows desktop for 20 minutes before recording temperatures with Core Temp. The 4 available core temperatures were then averaged out to give an overall temperature.

For load tests, we loaded up Prime 95 and ran the blend test for 20 minutes. This allowed the temperatures to settle and indicates the cooling ability of the unit. Running the tests for a longer amount of time did not alter the average temperatures by more than one degree. Once again the 4 available core temperatures were then averaged out to give an overall temperature. Ambient temperature was 28 degrees Celsius at time of testing.

Test 1 – Seidon 120M vs. Corsair H60 vs. Corsair H50 at stock (3.1GHz) (Idle + load)

Stock comparison chart

Stock comparison chart

Test 2 – Seidon 120M vs. Corsair H60 vs. Corsair H50 at overclock (4.2GHz) (Idle + load)

Overclocked comparison chart

Overclocked comparison chart

Test 3 – Seidon 120M single fan vs. Seidon 120M push-pull at stock (3.1GHz) (Idle + load)

Push pull Stock comparison chart

Push pull Stock comparison chart

Test 4 – Seidon 120M single fan vs. Seidon 120M push-pull at overclock (4.2GHz) (Idle + load)

Push pull Overclocked comparison chart

Push pull Overclocked comparison chart

Bottom line

The Seidon 120M may not be the best thing since sliced bread, but it’s good enough to be a worthy contender in the all-in-one cooling solution market. The performance is great, and it only gets better when you add a second fan into the mix. It can keep up and surpass some of the big names in the same category range and does so with a low-profile design. There are a few issues though. The stock fan can get incredibly loud, louder than most gamers want to deal with, and it gets worse when you add a second fan to the radiator. Luckily it is a PWM model so keeping the noise in check is possible, and even at lower fan speeds to reduce noise, performance is still good.

Other than the noise, everything went smoothly. From installation to aesthetics, the Seidon 120M has all the bases covered. If you’re in the market for a new cooler and absolutely want an all-in-one liquid cooling system the Seidon 120M may be for you – it comes recommended.

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