On Figure 15 you can see GameXstream 700 W label stating all its power specs.

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Figure 15: Power supply label.

What immediately caught our eye were the four separated +12 V lines listed on the label (see Figure 15). As it happens to all high-power units nowadays, OCZ 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, as you can see on Figure 16. The wires connected to +12V1 have a blue stripe, the wires connected to +12V2 have a green stripe, the wires connected to +12V3 are solid and the wires connected to +12V4 have a black stripe. This makes it easy to see that the ATX12V connector labeled as “CPU 1” is connected to +12V1, the second ATX12V connector labeled as “CPU 2” and the second auxiliary PCI Express connector labeled as “PCIE-2” are connected to +12V2, the motherboard main cable, the peripheral cables and the SATA cables are connected to +12V3, and the first auxiliary PCI Express connector labeled as “PCIE-1” is connected to +12V4.

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Figure 16: +12 V wires are separated into four virtual rails.

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Figure 17: But they are connected to the same +12 V line on the PCB.

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.

We found some funny things on this power supply label.

For the +12 V output OCZ stated 18 A for each one of the power supply four virtual rails. This would give a 216 W per rail or 864 W total – OCZ labeled +12 V total power as 680 W. Oh, there is a small phrase there “Maximum combined current for the +12 V outputs shall be 50 A”. Well, if we do the math, the maximum power for the +12 V outputs combined would be 600 W – and not 680 W as printed on the label. Why printing to conflicting numbers?

For the + 5 V output OCZ stated a 30 A maximum current, which translates to 150 W, while for the +3.3 V output the manufacturer stated a 36 A maximum current, or 118.80  W. On the label, however, OCZ 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). Here it is funny to notice that Corsair HX620W, a 620 W power supply, has a combined power of 170 W, more than this 700 W power supply.

Anyway, 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 700 W load to check if this power supply could deliver its labeled power or not.

Also, as a final note, OCZ doesn’t specify the temperature under which the power supply is rated. Usually when no temperature is stated, the manufacturers assume 25ş 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.