Cooler Master Extreme 2 475 W Power Supply Review

Secondary Analysis

The Cooler Master Extreme 2 475 W uses a regular design in its secondary, with Schottky rectifiers.

The maximum theoretical current that 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. As an exercise, we can assume a duty cycle of 30 percent.

The +12 V output uses two BYQ30E Schottky rectifiers, each supporting up to 16 A (8 A per internal diode at 104° C with a 1.25 V maximum voltage drop, which is extremely high, i.e., low efficiency). This gives us a maximum theoretical current of 23 A or 274 W for the +12 V output.

The +5 V output uses two STPS2045CT Schottky rectifiers, each supporting up to 20 A (10 A per internal diode at 155° C with a 0.84 V maximum voltage drop). This gives us a maximum theoretical current of 29 A or 143 W for the +5 V output.

The +3.3 V output uses another two STPS2045CT Schottky rectifiers, giving us a maximum theoretical current of 29 A or 94 W for the +3.3 V output.

It is very interesting to note how the +12 V output uses rectifiers that are “weaker” than the ones used on the +5 V and +3.3 V outputs, a typical scenario from 15 years ago. Nowadays, the +12 V output must be “stronger” than the other outputs, since the components that consume the most current from the power supply (namely, the CPU and the video card) are connected to the +12 V output.

Figure 13: One of the +3.3 V, +5 V, and +12 V rectifiers

This power supply uses a PS223 monitoring integrated circuit, which supports over voltage (OVP), under voltage (UVP), over temperature (OTP), and over current (OCP) protections. The over current protection has four channels (+5 V, +3.3 V, +12V1, and +12V2), correctly matching the number of +12 V rails advertised by the manufacturer (two).

Figure 14: Monitoring circuit

The electrolytic capacitors that filter the outputs are also from Teapo and labeled at 105° C, as usual.