Cooler Master MasterWatt Maker 1200 MIJ Review

Since CES 2017, where Cooler Master first showcased a limited edition, $1000 and all Made-in-Japan PSU, there is great hype all over internet about this PSU, the Cooler Master MasterWatt Maker 1200 MIJ Power supply. A PSU designed and made in co-operation of Cooler Master and Murata with over 165,000 work-hours of 40 Murata engineers, creating a power supply delivering the performance, reliability and quality one never thought possible.

And today we are honored to review the Cooler Master MasterWatt Maker 1200 MIJ Power supply, where MIJ stands for “Made in Japan". This is a 1200 W power supply, rated at 80 Plus Titanium efficiency levels (i.e. >94% energy efficiency), though Cooler Master claims this PSU is able to achieve >95% efficiency levels using the highest quality Japanese components available.

This PSU is designed from bottom-up using Dual switch Forward & Flyback converter topology in PFC stage. This topology is considered as one of the best and most reliable converter ever. The dual switch forward topology is better than a single-switch PFC circuit because it uses half the current and switching at twice the frequency making a PSU circuit better in signal, the overall figure of merit (FOM) and power loss measurements.

Murata have also custom designed more than 20 components especially for this PSU like Murata-made planar transformer which is superior to standard SMPS transformers due to its longer lifespan. If you are in electronics than you should have heard about Murata, if not let me share. Murata is a well-known electronics and components manufacturer (, providing parts to clients active in the fields of robotics, communications, automotive, data center, security and space exploration.

Now let's see whether this Cooler Master and Murata joint venture have really pushed the Computer Power Supply envelope to a new level and justify the $1000 price tag . Let's start.


  • Designed, made in Japan by Murata Manufacturing Co., Ltd.
  • Titanium 80+ efficiency
  • Fanless up to 600w (50% load)
  • Unique transformer design
  • 80% Japanese components
  • 10-year transferrable warranty
  • Fully modular cabling


Output Rating



Cooler Master MasterWatt Maker 1200 MIJ Power supply comes in a huge black/dark gray colour toned box with PSU securely packaged. Front of box showcase product graphics, Model name and 80 PLUS Titanium certificate. On the side and back of the box, specification and product briefings get their place.

Inside the box

Box opens with a flip-top cover revealing another box inside. Removing the top cover we are greeted with a note from Cooler Master Technology Inc.

Inside we see the PSU in center securely kept in place with thick black hard foam cutouts along with two hard zip pouches or carry-cases holding all the cables for the power supply.

With all that great packing and carry-cases we are really disappointed with the bundled cables, at a $1000 price tag one could expect a good quality individual sleeved cable set instead all cables are standard CM flat black ribbon type cables with PCIe cables having a custom high amp ratting plug end connector.


The MasterWatt Maker 1200 MIJ is slightly larger (224mm long) than your average PSU with solid tank like outer shell build quality. PSU is having top fan vents with a single 135mm Cooler Master Silencio FP fan for cooling which don't even operates up to 50 percent of PSU load.

On the rear side of the PSU beside the standard IEC connector, we were surprised to see such a small and low power main switch on a 1200W PSU, that seems inadequate, but later we found that instead of a physical line open/close switch this is a passive soft switch, preventing all inrush high current at power-on and eliminating terminal sparks at high loads. Good to see this soft switch implementation.


Now let's open this PSU and see what's inside.

WARNING : This can be painful to many, but I am enjoying a $1000 warranty void

First look, a very neat PCB Layout.

First let us talk about the cooling solution. A 135mm Cooler Master Silencio FP(Model: FA13525L12LPA) fan with 12v 0.5A rating is used for all cooling needs.

Below I will try to analysis different segments of this PSU, but before that let me take out the PCB for the case.

To isolate the underside of the PCB from the case metal, a thick black sheet of insulated material is used. Case also holds IEC mains connector with two transient filter Y-caps and thick main leads wrapped around a ferrite ring.

According to my observation I have divided the PCB layout into segments.

This PSU consists of three different Power supplies driving from main power but controlled / monitored via a single microcontroller. Just to brief out the main PCB hold the most power full 12v supply and remaining two daughter boards on either side of PCB, out of which one is used for 5v Stand-by and second board is all together a separate 130W PSU responsible for 5V and 3.3V DC.

1. The Transient Filter Stage. This section hold all the requisite components for proper implementation of Transient Filter Stage. The Coils and capacitors are properly stacked over each other for proper air flow and thermal management. This segment also holds the first main's fuse too, a 20A 250V HRC Fuse.

Underside of coils we have a Power Integrations CAP200DG, CAPZero-2 Zero1 Loss Automatic X Capacitor Discharge IC. Used here for managing the block current and discharge of X Cap in the transient filter stage giving ultra low ON-LOAD consumption and improving the overall PSU efficiency.

2. The main bride rectifier used is D2XB60, a 600V 25A bride rectifier diode.

3. The APFC section consists for two huge filet coils specially designed for long life and great efficiency.

You can also see two small driver transformers used to drive two separate PFC MOSFET arrays making up of Dual switch Forward PFC topology. The four MOSFETs used are Infineon 650V CoolMOS C7 Power Transistor IPP65R045C7 with a pulsed drain current of 212A at 25C. And two ROHM SCS220AM diodes are used as APFC boost diodes.

Each PFC MOSFET arrays have its own driver chip and isolating all the possible interference.

5. The main bulk capacitors are two Nippon Chemi-con caps with 830uf and 620uf capacitance and rated for 420VDC at 105C. These two caps are also paralleled via many surface mounting low capacitance capacitors at bottom side of PCB. Improving the filtration and lowering the high voltage noise.

4. This is the 5V Stand-by power supply board with its own fuse and management circuitry. This board also controls the soft power switch for turning PSU on/off via back switch.

6. This heatsink holds two MOSFETS TF27S60 Alpha & OMEGA semiconductor MOSFET each capable of handling a 60A at 600V

7. This is the second board all together a separate 130W PSU responsible for 5V and 3.3V DC, having all the requisite controller chips and capacitors on board. Even having its own main 250v fuse.

8. This section is the main 12V DC section holding the Murata-made planar transformer along with an array of surface mounted rectifier MOSFETs and a big copper busbar for terminal connection. The high amp 12V is passed through a pair of thick copper cables clamped onto the busbar over to the back modular connector PCB. All 12v black wire have a ferrite ring to edge out any low frequency noise or interference.

Also you can see a Panasonic relay for PSU On/off functionally .

9. The modular board is perfectly designed with proper layout. All high current interconnects are managed via thick copper busbars with each output terminal having its own Rubycon Capacitor to help in ripple managment.

Lastly meet the main microcontroller the Microchip PIC24FJ64GA306, A PIC24F 16-bit Microcontroller featuring nanoWatt XLP for eXtreme Low Power consumption and is suitable of lot of general purpose application. Here it is used to manage all protections and different segments on this PSU

After having a close look at inside of this PSU, I am totally impressed with the build quality of this PSU, from perfect PCB layout. A super good quality gold plated PCB, with high quality surface mounting components (as you can see those blue resistors are the precision resistors at wide thermal spectrum ) .

One can clearly see the effort and engineering went into making each custom component to work 100% upto its specifications. Like to point out few custom parts used in this PSU.

  • Custom PFC Coils.
  • APFC sense or driver transformers
  • The main 12v transformers and flat driver transformer
  • High current connectors
  • Load Test

    To test the PSU on my custom home-made Active load tester, I have manually increased the load in Amps on 12v first rail, 12v second rail, 5v and 3.3v rail to simulate 100%, 80% 50% and 20% load. Since this PSU is having only single 12v rail, so divided the load in half on both 12v loads on my tester.

    5V stand-by and -12V supply was left at a constant 1 amp and 0.5 amp respective load throughout the test run.

    Maximum theoretical load handling capacity of my tester is somewhat around 1500W, but due to MOSFETs safe operating area (SOA) characteristics and thermal load handling capacity of the heatsinks, this tester can handle Max 1300W.. For safety reasons I have also installed a thermal controller which turn OFF the attached PSU if temperature exceeds SOA specifications.

    Voltage Regulation and Efficiency

    Voltage Ripple

    We measured range of ripple using oscilloscope at maximum rating of the PSU for 12v, 5v and 3.3v supply output in Pk-Pk(mv).

    ATX specification for Ripple Pk-Pk(mv) for +12v is 120mv and for +5v and +3.3V it is 50mv. And following are our findings for this PSU


    To measure exact thermal performance of the PSU, we mounted our thermostat with proper thermals onto the Primary heatsink of the PSU and top cover with fan is closed properly. PSU kept under load about 3 minutes at different load settings. Before and after every test run, PSU and test equipments were turned OFF for half an hour.

    The Cooler Master MasterWatt Maker 1200 MIJ Power supply is a quit operational PSU with zero fan movement upto 600W of load and even at max load setting fan's rpm was very low and quite. I tested this PSU on an open bench, but when installed inside the Master 5 Case with all panels close, we are not able to hear any fan noise. Great job.


    • Made in Japan
    • Custom build Components
    • Fully Modular
    • Great packing
    • 10 years Warranty
    • Super High build quality
    • Ultra Low Ripple
    • Great Voltage regulations
    • Low fan noise even at max Load


    • No sleeved modular cables


    I was really surprised first when I heard about a $1000 PSU.. really !! But after personally looking at the actual product and build quality, I can no doubly say that the Cooler Master MasterWatt Maker 1200 MIJ Power supply is worth every penny of its $1000 price tag.

    The hard work and precision engineering of 40 engineers at Murata with +2 years of Research and Development are clearly seen in this power supply. From PCB to miniature SMD components, upto creation of custom components no inch or corner have left untouched to engineer a top notch quality product.

    A 10 years of warranty from Cooler Master on this power supply is way too low, when this power supply is build like a tank. Ones purchased I can ensure that you will not need any other PSU for next 20 years or so. This is a "Buy and Forget" type power supply.

    With an analog design, ultra low ripple and very quite working this is the PSU I would suggest for all Audio workstations, Audiophiles and for all those who only quality matters.

    There is nothing negative in this power supply that I could point out. But I was little disappointed about not finding sleeved modular cables with this power supply, especially with a $1000 price tag. If I can send $1000, than I would not mind adding few bugs more for premium quality sleeved modular cables. I would like to suggest Cooler Master to replace the flat ribbon cables with some quality sleeved modular cables or provide them as extra add-on accessories.

    Finally I can clearly say that the Cooler Master MasterWatt Maker 1200 MIJ Power supply is the best quality of consumer computer power supply ever made till date and worthy of our PC Tek Reviews Excellence Award.


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