Zalman ZM600-HP 600 W Power Supply Review

Secondary Analysis

Like OCZ StealthXstream 600 W and OCZ GameXstream 700 W this power supply uses eight Schottky rectifiers on its secondary. On Zalman ZM600-HP and OCZ GameXstream 700 W and they are all the same model: MBRP3045N. This is really unique, as usually power supplies use a different rectifier for each output. Four of them are used for the +12 V output, two of them are used for the +5 V output and two of them are used for the +3.3 V output – even though the +3.3 V output uses a separated rectifier, it is connected at the same transformer outputs as the +5 V line.

OCZ GameXstream 600 W uses four MBRP3045N and four MBR2045CT and this is the main difference between this power supply and the other two. The four MBR2045CT rectifiers are used to produce the +12 V output and they have a lower maximum current/power (20 A vs. 30 A). So the main difference between OCZ StealthXstream 600 W and the other two power supplies based on the same design is the +12 V output.

Each MBRP3045N rectifier can handle up to 15 A per diode or 30 A per device (rated at 100° C). 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 output uses four 15 A diodes in parallel. This would give us a maximum theoretical current of 86 A or 1,029 W for the +12 V output.

The +5 V output uses two 15 A diodes in parallel. This would give us a maximum theoretical current of 43 A or 214 W for the +5 V output.

The +3.3 V output uses two 15 A diodes in parallel. This would give us a maximum theoretical current of 43 A or 141 W for the +3.3 V output.

The maximum current each line can really deliver will depend on other components, in particular the coil used.

As you can see, the rectifiers are clearly overspec’ed.

Figure 17: The eight Schottky rectifiers used on the secondary.

In Figure 19 you have a better picture of the heatsink used on the secondary.

Figure 18: Secondary heatsink.

There is a thermal sensor located under the secondary heatsink. You can see this thermal sensor in Figure 19 (we removed the secondary heatsink to take this picture).

Figure 19: Thermal sensor.

This power supply uses Taiwanese electrolytic capacitors from Teapo and OST rated at 105° C on its secondary. This power supply uses exactly the same capacitors as OCZ GameXstream 700 W and OCZ StealthXstream 600 W.