OCZ StealthXStream 600 W Power Supply Review

Secondary Analysis

Like Zalman ZM600-HP and OCZ GameXstream 700 W this power supply uses eight Schottky rectifiers on its secondary, however the rectifiers are different and here lies the difference between OCZ StealthXstream 600 W and these other two power supplies. While on these other two power supplies all eight Schottky rectifiers are identical (MBRP3045N), OCZ StealthXstream 600 W uses four MBRP3045N, two for the +5 V output and two for the +3.3 V output, and four MBR2045CT for the +12 V output.

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 M
BRP3045N rectifier can handle up to 30 A (15 A per internal diode, rated at 100° C) while each MBR2045CT rectifier can handle up to 20 A (10 A per internal diode, rated at 135° C).

The maximum theoretical current the +12 V 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%.

This would give us a maximum theoretical current of 57 A [(10 A x 4) / (1 – 0.30)] or 686 W for the +12 V output on OCZ StealthXStream 600 W, while Zalman ZM600-HP and OCZ GameXStream 700 W have a maximum limit of 86 A [(15 A x 4) / (1 – 0.30)] or 1,029 W for the same output.

Since these three power supplies use the exact same rectifiers and design for the +5 V and +3.3 V outputs, the maximum theoretical capacity is the same: 43 A [(15 A x 2) / (1 – 0.30)] for each output, i.e., 214 W for the +5 V output and 141 W for the +3.3 V output.

The maximum power the power supply can deliver depends on other components used.

Figure 12: The eight Schottky rectifiers used on the secondary (four on each side of the heatsink).

This power supply has a thermal sensor located under the secondary heatsink, which controls the fan speed according to the power supply temperature. You can see this thermal sensor in Figure 13 (we removed the secondary heatsink to take this picture).

Figure 13: Thermal sensor.

This power supply uses Taiwanese electrolytic capacitors from Teapo, CapXon and OST. The big electrolytic capacitors from the active PFC circuit is rated 105° C like all other smaller capacitors are rated 105° C.