Before performing our overload tests we always like to test first if the over current protection (OCP) circuit is really active and at what level it is configured.

We configured +12V1 input from our load tester with a low current (1 A) and increased current on +12V2 input (which was connected to the power supply +12V1 rail) until the power supply shut down. This happened when we tried to pull more than 18 A, which is great, meaning that OCP is really active and only 2 A above what is printed on the label (16 A).

The maximum amount of power we could pull from Zalman ZM600-HP with it still working inside ATX specs can be found below. Even at this extreme configuration noise level was still halfway the maximum allowed, peaking 60 mV at +12V2 and 24.4 mV at +5 V.

As you can see, we could not only pull 740 W from this power supply at 45º C, but it was still maintaining efficiency above 80%!

Above this configuration the power supply would not turn on, showing its protections in action. So you don’t need to be afraid, this unit won’t die or explode if you pull more than it can handle.