Cooler Master Real Power 550

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The interior is almost identical to the 450W version. Only a different model number on the main transformer and a few differently placed parts indicate that these are not identical PSUs. Even the airflow deflector that directs air through the middle of the power supply is in the same position.

Two aluminum heatsinks serve the dual role of heat dissipation and directing airflow towards the exhaust.

The interior of the 450W version. The basic layout is identical; the differences are in the quality of the components used.

A small plastic square deflects airflow towards the yellow-topped main transformer.

The fan in the 450W model was a weak point, and things look no better in the 550W model. The two fans seem quite similar. Both are dual ball bearing designs that bear Cooler Master's logo. The fan in the 550W model is rated for 0.45A — more than the 450W model — which suggests that it will be faster and louder.

Dual ball bearings and a 0.45A rating are signs of a high speed fan.


There are a total of eight cable sets, plus a thin cable that operates the power meter and a 24 to 20-pin adaptor for the main ATX connector:

The longest cable is three feet long.

  • 18" sleeved cable for the main 24-pin ATX connector
  • 19" 4-pin auxiliary 12V connector
  • 19" 8-pin auxiliary EPS connector for EPS12V (dual CPU) systems
  • 19" 6-pin EPS Workstation connector (2 x +3.3V, 2 x +12V2, 2 x neutral)
  • 18" 6-pin PCIe connector
  • 31" cable with three 4-pin IDE drive connectors
  • 36" cable with three 4-pin IDE drive connectors and one floppy drive power connector
  • 31" cable with three SATA drive connectors
  • 23" proprietary Human Computer Interface cable (+6" on HCI itself)
  • 6" 24 to 20-pin adaptor

The EPS Workstation connector is unusual, and deserves some explanation. Like the PCIe connector, it is designed to supply auxiliary power to a powerful VGA card. It even uses an identical plug, but the pin layout is not identical so extreme care should be taken to ensure that it is not used in place of a PCIe connector. Doing so could easily fry the card it is connected to and possibly the power supply itself. For the record, the EPS connector is white and the PCIe connector is black.

So, what use is a plug that provides auxiliary power to a VGA card without any compatible VGA cards? The EPS Workstation connector is designed to supply extra power to the motherboard, which then passes the power on to the VGA card through the PCIe slot.

Care should also be taken in an SLI system with two cards that require PCIe connectors. Because the Real Power only provides one of these connectors, an adapter must be used for the second connector. However, the Molex connectors that such adapters draw their power from draw from the less powerful +12V3 rail, not the +12V2 rail that is designed to handle a heavy load. Although it's hard to imagine such a setup continuously drawing more current than the 6A rating on the +12V3 rail, it does place it under a disproportionate load, which could lead to odd voltage fluctuations.

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