The Silent Pro Gold series uses a very different design in its secondary. First, the transformer has an embedded heatsink. This design is being called “Hybrid Transformer” by Cooler Master and according to them it allowed the transformer to be reduced 25%. Then the transistors used as rectifiers are placed as close as possible to the transformer terminal in order to reduce loss caused by longer routes on the power supply printed circuit board. In fact these transistors are soldered on a small printed circuit board together with the transformer, and the transformer and the transistors are added to the main printed circuit board as if they were a single piece. This design is being called “Hyper Path” by Cooler Master.

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Figure 14: “Hybrid Transformer” and “Hyper Path” designs.

As could be implied by the explanation above, this power supply uses a synchronous design, which means the Schottky rectifiers were replaced with MOSFET transistors. This change allows the power supply to achieve higher performance.

On top of that this unit uses a DC-DC design, meaning that it is basically a +12 V power supply with the +5 V and +3.3 V outputs being generated using two separated switching power supplies connected to the +12 V rail. This design is proving to be the best choice in order to achieve high efficiency.

Two IPP023N04N MOSFETs are used to produce the +12 V rail and, as explained, are installed on the transformer module. Each transistor is capable of delivering up to 90 A at 100º C with an RDS(on) of only 2.3 m§Ù, which provides very little loss (i.e., increases efficiency).

The maximum theoretical current each line can deliver is given by the formula I / (1 - D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode. Just as an exercise, we can assume a typical duty cycle of 30%.

The +12 V rail is also used by the +5 V and +3.3 V rails as well; if all power was pulled from the +12 V rail alone, we are talking about a maximum theoretical current of 129 A or 1,543 W at 100º C.

Of course this is a theoretical number and we are just doing an exercise here. The real amount of current/power each output can deliver is limited by other components.

In Figures 15 and 16 you can see one of the DC-DC modules (the unit has one for the +5 V output and one for +3.3 V output). Each DC-DC module has two STD85N3LH5 (55 A at 100º C, 5.4 m§Ù resistance) and two IPD060N03L (50 A at 100º C, 6 m§Ù resistance) transistors and one APW7073 PWM controller.

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Figure 15: DC-DC conversion module.

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Figure 16: DC-DC conversion module.

The outputs are monitored by a PS232S integrated circuit that is soldered on the printed circuit board shown in Figure 12. This circuit supports over voltage (OVP), under voltage (UVP) and over current (OCP) protections. The interesting thing is that this circuit offers six over current protection channels (one for +3.3 V, one for +5 V and four for +12 V), but the manufacturer decided to configure this unit as a single-rail product, using only one of the +12 V OCP channels available.

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Figure 17: Monitoring circuit.

All capacitors present on the main printed circuit board are also Japanese, from Chemi-Con, but some Taiwanese capacitors from Teapo are used on the modular cabling system. So although the manufacturer advertises this unit as having Japanese capacitors, it is important to bear in mind that this doesn’t mean that ALL capacitors are made in Japan.