Cooler Master Silent Pro M 600 W Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of Cooler Master Silent Pro M 600 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one BU1506 rectifying bridge, which supports up to 15 A at 85° C if a heatsink is used (which is the case) or only up to 3.4 A at 25° C if it is not installed to a heatsink. At 115 V this unit would be able to pull up to 1,725 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 1,380 W without burning itself out. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

Figure 9: Rectifying bridge.

Two STW20NM50 power MOSFET transistors are used on the active PFC circuit, each one capable of delivering up to 20 A at 25° C or up to 12.6 A at 100° C in continuous mode (note the difference temperature makes), or up to 80 A at 25° C in pulse mode, presenting an RDS(on) of 250 mΩ (resistance when the transistor is turned on; the lower this number the better, meaning higher efficiency).

This power supply uses two electrolytic capacitors to filter the output from the active PFC circuit. The use of more than one capacitor here has absolute nothing to do with the “quality” of the power supply, as laypersons may assume (including people without the proper background in electronics doing power supply reviews around the web). Instead of using one big capacitor, manufacturers may choose to use two or more smaller components that will give the same total capacitance, in order to better accommodate space on the printed circuit board, as two or more capacitors with small capacitance are physically smaller than one capacitor with the same total capacitance. Cooler Master Silent Pro M 600 W uses two 270 µF x 420 V capacitors in parallel; this is equivalent of one 540 µF x 420 V capacitor. These capacitors are Japanese, from Matsushita and labeled at 85° C.

The reviewed power supply uses two STP20NM50FD power MOSFET transistors on its switching section, installed on the traditional two-transistor forward configuration. Each transistor can handle up to 20 A at 25° C or up to 14 A at 100° C in continuous mode, or up to 80 A at 25° C in pulse mode, with a maximum RDS(on) of 250 mΩ.

Figure 10: Switching transistors, active PFC diode and active PFC transistors.

The primary is controlled by a CM6806 PFC/PWM combo controller.

Figure 11: PFC/PWM combo controller.

Now let’s take a look at the secondary of this power supply.