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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.

Zalman ZM600-HPFigure 17: The eight Schottky rectifiers used on the secondary.

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

Zalman ZM600-HPFigure 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).

Zalman ZM600-HPFigure 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.

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Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.