Review of the power supply Cooler Master MasterWatt 650 with a capacity of 650 watts /


Cooler Master has long been known in the domestic market for its cooling systems, cases and power supplies. About 20 years ago, its main product was CPU coolers, discreet in appearance, but effective in their capabilities. After that, she was one of the first to offer aluminum chassis and fueled CBOs.

Now the popularity of this brand is due to affordable cases and cooling systems, but its assets still have power supplies, although they are not so actively promoted in our market. In general, the company does not stop developing the direction of power supplies, and we will just get acquainted with one of the new products of the MasterWatt series in this review.

Cooler Master MasterWatt 650

Cooler Master MasterWatt 650 (MPX-6501-AMAAB)

The device in question belongs to the recently released Cooler Master models, with power from 450 to 750 watts and meeting the 80 Plus Bronze standard. All of them are “semi-modular”, i.e. only part of the power cables are unfastened in them, and the forced cooling system is activated only after 15% of the load on the unit. And, of course, such solutions are promised a 5-year warranty.

The block is supplied in black packaging, which shows the device itself and the main characteristics and capabilities of the purchased device.

The delivery set does not abound with anything superfluous, only everything you need for installation in the system: instructions, a set of mounting screws, detachable cables and a power cord. The block, by the way, has a very original protection for transportation.

Cooler Master MasterWatt 650

The power cable for the motherboard (55 cm) and the processor (4 + 4; 60 cm) are stationary, the rest look like this:

  • two with two 8-pin (6+2) connectors for powering PCI-E video cards (55 cm);
  • two with four power connectors for SATA devices (50+12+12+12 cm);
  • one with one power connector for SATA devices, three power connectors for IDE devices and one for FDD (50+12+12+12+12 cm).
Cooler Master MasterWatt 650

All cables are flat, stationary are additionally enclosed in a nylon braid. This amount is enough to build a system with a large number of different equipment.

Externally, due to the black color, the unit does not stand out much from other solutions for the retail market, only a stamped 120-mm fan grill adds a touch of originality.

Cooler Master MasterWatt 650

On the inner panel there are connectors for detachable cables. For each type, the corresponding connector is selected and it will be problematic to confuse them when connecting them.

Cooler Master MasterWatt 650

MasterWatt 650 has modern characteristics and is capable of delivering its nominal value of 650 W via the +12V line. The combined power of the low-voltage channels is 120 W, which should be enough for the systems of the latest generations.

Cooler Master MasterWatt 650

For the standby voltage and the -12V line, 3 and 0.3 amperes are provided, respectively.

Cooler Master MasterWatt 650 +3.3V +5V +12V1 –12V +5Vsb
Max. load current, A 22 22 54,1 0,3 3
Combined power, W 120 650 3,6 15
Total maximum power, W 650

There is an APFC module and the ability to work in a wide range of mains voltage. Of the protections declared from low and high voltage, from short circuit, overload of output lines, from overheating. There is also an automatic fan speed control.

Remove the lid … And the lid was not so easy to remove. The body of the block consists of two U-shaped halves that are inserted into each other. The solution is original, but not very convenient for, for example, replacing a failed fan.

Cooler Master MasterWatt 650

So, under the cover was the HEC platform based on a push-pull forward converter with a Schottky diode rectifier and DC/DC converters.

Cooler Master MasterWatt 650Cooler Master MasterWatt 650

Despite the modularity of the design, the depth of the case is only 140 mm, and the printed circuit board turned out to be even more compact, while no particular density of mounting elements was noticed.

Cooler Master MasterWatt 650

The input filter is divided into two parts: one is located directly on the main board, and the second is combined with a network connector and a switch.

Cooler Master MasterWatt 650Cooler Master MasterWatt 650

The power elements are cooled by small heatsinks with good fins; a small plate with petal fins is provided for a pair of diode bridges. A temperature sensor is located on the radiator of the output circuit elements.

Cooler Master MasterWatt 650

The block is controlled by a PWM controller CM6800TX. Two separate DC / DC converters are made on APW7164 chips, located on separate boards near the rectifier heatsink, while the inductance of each converter is soldered to the main board. For monitoring, a WT7527W chip was installed, also on a separate board.

Electrolytic capacitors are used by Teapo. The input circuit stands at 470 uF with an operating voltage of 400 V and a temperature of 85 °C. There are also polymer ones in the DC/DC converter.

Cooler Master MasterWatt 650Cooler Master MasterWatt 650

There are also several electrolytic capacitors on the connector board. The board itself is rigidly attached to the main PCB, which made it possible to design the unit in such a compact package.

Cooler Master MasterWatt 650

The quality of the soldering generally does not cause any complaints, however, there are traces of excess solder and noticeable manual intervention after the automatic line.

Cooler Master MasterWatt 650

The unit is cooled by a 120mm DF120251212RFLN fan with a maximum rotation speed of 2500 rpm and a two-pin connection.

Cooler Master MasterWatt 650

The main feature of this model is the self-lubricating bushing with IP6X level dust protection.

Cooler Master MasterWatt 650

When starting the system and in idle mode, the fan was completely stationary, but as the load increased, from a fixed 710 rpm, its speed increased to 830 rpm with a slight buzz. It’s about game mode. If you increase the power consumption, then the speed reaches up to 2255 rpm, while the noise level is appropriate.

Test Methodology

It is difficult to carry out full testing without an appropriate stand, so the power supplies were tested using a conventional system assembled from the following components:

  • processor: Intel Core i7-6700K (4.0@4.5 GHz);
  • motherboard: ASUS Maximus VIII Formula (Intel Z170);
  • Cooler: Prolimatech Megahalems;
  • RAM: HyperX HX430C15PB3K2/16 (2×8 GB, DDR4-3000, 15-16-16-35-1T);
  • video cards: GeForce GTX 1080;
  • drive: Kingston SSDNow UV400 240GB (240 GB, SATA 6Gb/s).

Testing was carried out in the Windows 10 x64 environment on an open stand. The Valley benchmark was used to create a game load on the system, and LinX 0.6.7 was launched in parallel for additional load.

Also, for maximum load, the following system was assembled:

  • processor: Intel Core i7-975 (3.33@4.02 GHz, Bclk 175 MHz);
  • motherboard: ASUS P6T7 WS SuperComputer (Intel X58);
  • cooler: Noctua NH-D14;
  • RAM: Kingston KHX2000C8D3T1K3/6GX (3×2 GB, DDR3-2000@1750, 8-8-8-24);
  • video cards: ASUS ENGTX295/2DI/1792MD3/A and Inno3D GeForce GTX 295 Platinum Edition (GeForce GTX 295);
  • hard disk: Samsung HD502HJ (500 GB, 7200 rpm, SATA-II).

Here testing was carried out in the Windows 7 x64 HP environment on an open bench. To create a load on the system, the OCCT 3.1.0 utility was used with a 30-minute power supply test. An Inno3D GeForce GTX 295 Platinum Edition card was used for additional workload. A mode was also enabled when one GeForce GTX 295 adapter was with SLI disabled. Such combinations made it possible to evenly increase the load on the block.

To measure the total power consumption of the system, the Seasonic Power Angel was used, which can also measure the power factor, voltage and frequency in the network, the consumed current and the amount of energy spent per unit of time. Net power consumption calculated based on 80 Plus certification – i.e. possible efficiency of the device. Errors in such calculations can be 5%. The voltages were checked with a UNI-T UT70D digital multimeter.

In addition, we decided to slightly expand testing by taking temperature readings inside the power supply, fan speed and noise level under a particular load.

The temperature was measured using the Scythe Kaze Master Pro panel, the sensors of which were located on the radiators inside the block and at a distance of 1 cm in front of the fan (#1) and behind the outer wall (#2).

Cooler Master MasterWatt 650

For fan speed results, a UNI-T UT372 non-contact tachometer was used. The maximum speed was fixed for each of the power supply testing modes.

It should be borne in mind that such a technique at this stage is far from ideal and will be supplemented and changed as it is used.

Test results

The obtained data are entered in the table. In brackets for voltage are percent deviations from the norm, for power consumption – the approximate net load on the power supply.

GTX 1080 GTX 1080 GTX 295 (LGA1366) GTX 295/2 (LGA1366) GTX 295 + GTX 295 (LGA1366)
Mode Idle Burn, Game+LinX Idle Burn, OCCT Burn, OCCT
Power consumption, W 38,4 (~31) 355 (~300) 188 (~155) 539 (~450) 771 (~630)
Line +3.3V, V 3,36 (+1,8) 3,34 (+1,2) 3,36 (+1,8) 3,34 (+1,2) 3,3
Line +5V, V 5,05 (+1) 5,04 (+0,8) 5,03 (+0,6) 5 4,96 (–0,8)
Line +12V1 (MB), V 12,13 (+1,1) 12,10 (+0,8) 12,14 (+1,16) 12,09 (+0,75) 12,07 (+0,9)
Line +12V2 (CPU), V 12,14 (+1,16) 12,08 (+0,7) 12,13 (+1,1) 12,06 (+0,5) 12,03 (+0,25)
Line +12V3 (VGA1), V 12,14 (+1,16) 12,08 (+0,7) 12,12 (+1) 12,06 (+0,5) 11,98 (–0,17)
Line +12V4 (VGA2), V 12,14 (+1,16) 12,11 (+0,9) 12,13 (+1,1) 12,11 (+0,9) 12,05 (+0,4)
Fan rotation speed, rpm 829 710 1360 2255
Thermosensor No. 1 26,3 25,7 25,8 26,6 26,7
Thermosensor #2 27,1 36,7 32,3 36,1 35,9
Thermosensor No. 3 48 43,3 39 48,1 48,3
Thermosensor No. 4 58,9 68,8 59 90,5 94

Good stabilization and good noise characteristics at medium loads allow you to assemble a productive gaming system with a moderate noise level. But the heating of the radiator in the output circuit at a power close to the nominal one, the temperature of which can reach an average of 94 ° C, is embarrassing.


The tested novelty may well be a good choice for building a powerful gaming system based on a top-end graphics accelerator, and even a couple of less productive modern solutions without overclocking. Quiet lovers won’t be left out either, thanks to silent mode at minimum load and moderate noise levels at medium load. In addition, the compact size of the MasterWatt 650 allows you to install the unit even in small cases. The only thing that confuses in it is the heating of the radiator of the output circuit, but the manufacturer guarantees trouble-free operation of the device for 5 years, which means that he is confident in his product. After all, it was not in vain that even a fan with dust protection was installed. And only the presence of a large number of competitors in the price range of about 70-80 dollars can affect the user’s choice.


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