Articles: Cases/PSU

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CoolerMaster Real Power Pro RS-C50-EMBA-D2 (1250W)

Unlike Akasa, CoolerMaster has already taken part in our tests, yet the two companies have something in common. Like the PowerMax, the Real Power Pro is manufactured by Enhance, but based on a different, more advanced, platform. So, it will be interesting to compare the two PSUs with each other.

The actual manufacturer is indicated by the UL certificate number on the label: E166947. By the way, you can see the same number certificate on the label of the Akasa PSU.

This model comes in a rather large black-and-white box with a carry handle.

Exterior Design

The PSU is rather large. The Akasa PowerMax was designed exactly to match the 135mm fan, but this model has a few extra centimeters. You can also see a huge socket for a power cord: it is only necessary for countries with 110V power mains but will provoke some problems elsewhere, especially for users who want to connect an UPS.

The PSU has fixed power cables including:

  • Mainboard cable with a 20+4-pin connector (63cm long)
  • CPU cable with a 4-pin connector (65cm)
  • CPU cable with an 8-pin connector (64cm)
  • Three graphics card cables with one 8-pin and one 6-pin connector on each (63+14cm)
  • Three graphics card cables with one 6-pin connector on each (63cm)
  • Two cables with four SATA power connectors on each (65+14+14+14cm)
  • Two cables with two Molex connectors and one floppy-drive plug on each (65+15+15cm)
  • One cable with three Molex connectors (65+15+15cm)

The cables have a typical length for this class of PSUs but it is rather odd to see a modern PSU that has more connectors for PATA than for SATA drives. Most users don’t have a single PATA device in their system already and use Molex connectors for system fans only. Of course, there are various adapters available for Molex plugs, but I guess a 1250W power supply should provide everything necessary without any adapters.

Interior Design

Although there is some similarity with the Akasa PSU, this one is based on a different platform. The Real Power Pro uses two power transformers, each rated for 50% of the PSU’s total output power. There are no special advantages about this circuit design. It is a forced solution because the PSU housing could not accommodate one full-wattage transformer (to remind you, this PSU has a wattage rating of 1250W). As transformers are getting smaller thanks to higher converter frequencies, new materials for the cores and other such technical advances, dual-transformer platforms lose their ground as being too complex and expensive.

The heatsinks are larger than in the Akasa. You will see below how this affects the cooling of the PSU.

There are Teapo capacitors on the output. As I’ve already said above, they have a good reputation.


Having a max output power of 1250W, the PSU can yield 1125W across its +12V power rail split into six “virtual” output lines with a max current of 20-28A each. The load capacity of the +5V and +3.3V rails is very high but does not bring any tangible benefits because modern computers consume no more than a few dozen watts from them.

UPS Compatibility

Together with an APC SmartUPS SC 620 this power supply worked at loads up to 430W when powered by the mains and the pair switched to the batteries without problems, but I had to reduce the load to 300W to ensure stable operation. Otherwise, the UPS would shut down in half a minute reporting overload. Thus, your UPS should have a sufficient reserve of wattage or sinusoidal output voltage in order to work normally with this power supply.

Output Voltage Stability

The PSU copes with any permissible load. None of the voltages violates the allowable limits, the +12V keeping within a 2% deflection from the nominal value.

Output Voltage Ripple

The output voltage ripple is rather high at full load but fits within the allowable range (although nearly reaching the limits on the +3.3V rail)


The PSU is cooled with a 135x135x25mm fan from Young Lin Tech. Having exactly the same fan, the Akasa PowerMax has smaller heatsinks. Does it mean the Real Power Pro is quieter?

Alas, it is not. The bottom fan speed (about 1100rpm, which is audible but comfortable) is only maintained until a load of 300W. Then it begins to grow up in a linear way. The PSU is very loud at loads above 600W. This again confirms my point that neither large heatsinks nor large fans, nor a high wattage rating can guarantee you silence. A lower-wattage and smaller PSU can prove to be much quieter at the same load.

Efficiency and Power Factor

The PSU is 80% efficient at a load of about 100 watts and improves up to 88% at the peak. Then, as the load grows up further, the efficiency declines steadily to 82%.

It looks like 75-80% efficient PSUs are a thing of the past. Today’s products generally have higher efficiency and the Real Power Pro is a good example.

Standby Source

The PSU barely copes with the maximum load on the standby source: at a current of 6A, its output voltage is 4.77V, the bottom limit being 4.75V.


Frankly speaking, the only reason you may want to buy a Cooler Master Real Power Pro RS-C50-EMBA-D2 is that you are absolutely sure your computer needs those 1250 watts of power. Although good in terms of electrical parameters, the PSU is a mediocre product overall. It is large and has a noisy fan. It is also unstable with UPSes and has a nonstandard socket for the power cord.

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