The most interesting thing that we discovered opening this power supply is that Zalman ZM600-HP and OCZ GameXstream 700 W are internally the same power supply, manufactured by FSP, using exactly the same components.

Both use a 120-mm fan on their bottom, have high-efficiency, have active PFC using three MOSFET transistors (while the usual is using only two) and carry a three-year warranty.

There are some differences, though. OCZ GameXstream 700 W does not provide a modular cabling system, while Zalman ZM600-HP does. Also the model from OCZ has a voltage regulator integrated circuit used as protection on its output, circuit not found on Zalman’s. And Zalman’s unit has a heatsink with heat-pipe on its secondary, while OCZ uses a L-shaped heatsink connected to the power supply housing, using it to dissipate the heat produced by the secondary rectifiers.

While the gauge of all main wires is the same on both power supplies (18 AWG), on OCZ GameXstream the +12 V (yellow) wires on the motherboard cables are 16 AWG, which can explain the higher current capability found on OCZ’s model.

While all components on both power supplies are exactly the same, the main rectifying bridges used on Zalman’s is one step above the ones used on OCZ’s (GBU606 vs. GBU605). While both components are basically the same, the bridges used on Zalman’s can handle a higher voltage.

Why OCZ model is labeled 700 W and Zalman’s is labeled 600 W is still a mystery to us, as they use the same circuit. The difference is on the +12 V outputs, and this difference could be explained by the use of thicker +12 V wires on GameXstream 700 W motherboard connectors.

Unfortunately we do not have a load tester to pull the labeled power from these power supplies, so we cannot say if they can really deliver their labeled power or not (an equipment like this costs around USD 10,000 in the US and we hope to buy one someday).

We found out that both power supplies don’t have a MOV (surge suppressor), which is a sin on a high-end power supply.

As for the temperature, both OCZ and Zalman don’t state under which temperature they labeled their power supply. Why this is important? The higher the internal power supply temperature, the lower power it can deliver. Usually when no temperature is mentioned, the manufacturer assumes 25º C. You will never get 25º C inside a power supply; typical real-world values are found between 35º C and 40º C. So a power supply labeled at 25º C may not deliver its labeled power when running in the real world.

So which power supply should you buy, Zalman ZM600-HP or OCZ GameXstream 700 W? We found Zalman ZM600-HP being sold at a little higher price, however it features a modular cabling system. If you don’t care about this feature, OCZ GameXstream 700 W is a better buy because it is cheaper and, like we said, is the same product. But if you are looking for modular cabling system and think that having a heat-pipe on the secondary heatsink something worth spending a little bit more, go ahead and buy Zalman ZM600-HP.

As a final note we want to stress how we liked the fact that Zalman printed on the power supply box the main design differences of their ZM600-HP compared to competing products, like the use of two rectifying bridges, three MOSFET transistors on the active PFC circuit and four Schottky rectifiers for the +12 V output. Since very little people have the technical background to evaluate power supplies, this helps a lot to educate users that not all high-end power supplies are the same.