On Figure 20 you can see ZM600-HP label stating all its power specs.

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Figure 20: Power supply label.

What immediately caught our eye were the four separated +12 V lines listed on the label (see Figure 20). As it happens to all high-power units nowadays, Zalman uses a “virtual rail” concept, where they label their power supplies as having separated +12 V rails but inside the unit they are all connected together to a single +12 V rail on the power supply printed circuit board. Unfortunately all manufacturers seem to be doing like this to match the ATX12V 2.x and EPS12V specifications, which require the power supply to have separated +12V rails.

Inside the power supply the wires are really separated into four virtual rails. The wires connected to +12V1 have a blue stripe and are connected to the main ATX12V/EPS12V cable, the wires connected to +12V2 have a green stripe and are connected to the second ATX12V/EPS12V/PCI Express 2 connector, the wires connected to +12V3 are solid and are connected main motherboard cable and peripheral cables and the wires connected to +12V4 have a black stripe and are connected to the main auxiliary PCI Express cable. This is exactly the same configuration used by OCZ GameXstream 700 W.

From the previous page we came with some maximum theoretical numbers for the +12V output (1,440 W), +5 V (300 W) and +3.3 V (198 W).

As we mentioned earlier the maximum current/power each line can really deliver will depend on other components, especially the transformer, the coil, the capacitor, the wire gauge and even the width of the printed circuit board traces used.

For the +12 V output Zalman stated 16 A for each one of the power supply four virtual rails – OCZ states 18 A for its GameXstream 700 W. This would give a 192 W maximum per rail or 768 W maximum total – Zalman labeled +12 V total power as 504 W.

For the + 5 V output Zalman stated a 24 A maximum current (GameXstream 700 W is labeled as 30 A), which translates to 120 W, while for the +3.3 V output the manufacturer stated a 24 A maximum current (GameXstream 700 W is labeled as 36 A), or 79.2 W. On the label, however, Zalman says that the combined power of +3.3 V and +5 V outputs is of 155 W (since they are connected to the same transformer output) – the same combined current labeled on OCZ GameXstream 700 W.

All positive outputs are labeled with a current well below the maximum current each rectifier can deliver.

Unfortunately we don’t have the necessary equipment to make a true power supply review; we would need to create a real 600 W load to check if this power supply could deliver its labeled power or not.

Also, as a final note, Zalman doesn’t specify the temperature under which the power supply is rated. Usually when no temperature is stated, the manufacturers assume 25º C, which is a temperature far below the power supply real working temperature. Keep in mind that the maximum power a power supply can deliver drops as its internal temperature increases.