OCZ StealthXStream 2 600 W Power Supply Review

Transient Filtering Stage

As we have mentioned in other articles and reviews, the first place we look when opening a power supply for a hint about its quality, is its filtering stage. The recommended components for this stage are two ferrite coils, two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor), and one MOV (Metal-Oxide Varistor). Very low-end power supplies use fewer components, usually removing the MOV and the first coil. 

This power supply has all required components but the MOV, which is in charge of removing spikes coming from the power grid. On the other hand, it has two Y capacitors and two X capacitors more than the minimum required.

Figure 8: Transient filtering stage (part 1)

Figure 9: Transient filtering stage (part 2)

In the next page we will have a more detailed discussion about the components used in the StealthXStream 2 600 W.

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On this page we will take an in-depth look at the primary stage of the OCZ StealthXStream 2 600 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two GBU606 rectifying bridges connected in parallel, both attached to the same heatsink used by the switching transistors. Each bridge supports up to 6 A at 100° C so, in theory, you would be able to pull up to 1,380 W from a 115 V power grid. Assuming 80% efficiency, the bridges would allow this unit to deliver up to 1,104 W without burning themselves out. Of course, we are only talking about these components, and the real limit will depend on all the other components in this power supply. These are the same components used on the original StealthXStream 600 W.

Figure 10: Rectifying bridges

The active PFC circuit uses two SPA20N60C3 MOSFETs, each one capable of delivering up to 20.7 A at 25° C or up to 13.1 A at 100° C in continuous mode (note the difference temperature makes), or up to 62.1 A in pulse mode at 25° C. These transistors present a 190 mΩ resistance when turned on, a characteristic called RDS(on). The lower this number the better, meaning that the transistors will waste less power and the power supply will have a higher efficiency.

Here we could see a difference between the original StealthXStream 600 W and the new StealthXStream 2 600 W. Even though the model of the transistors is he same, the older model has three transistors in its active PFC circuit, while the new model carries two. The StealthXStream 2 600 W has a space where the third transistor was installed.

Figure 11: Active PFC transistors and diode

The electrolytic capacitor used to filter the output of the active PFC circuit is from OST and labeled at 105° C.

In the switching section, another two SPA20N60C3 MOSFET transistors are used. The specifications for these transistors are already published above. The original StealthXStream 600 W use transistors that are a little bit "weaker" here (18 A at 25° C, 12.1 A at 100° C, 265 mΩ resistance).

Figure 12: Switching transistors

The primary is controlled by the omnipresent CM6800 active PFC/PWM combo circuit.

Figure 13: Active PFC/PWM combo controller

Now let’s take a look at the secondary of this power supply.