Before overloading power supplies we always test first if the over current protection (OCP) circuit is active and at what level it is configured.

In order to do that we configured the +12V1 input from our load tester (which was connected to the power supply +12V2 rail) with a low current and configured our load tester to pull 33 A from the power supply +12V1 rail. The power supply turned on, meaning that either OCP is disabled or configured at a value above 33 A.

Then starting from test five we increased currents to the maximum we could with the power supply still running inside ATX specs. The problem was that the power supply burned under this condition. Then we requested a second sample from Seventeam and the same thing happened. With our first sample we were pulling 32 A from each +12 V rail and 10 A from +5 V and +3.3 V, for a total of approximately 850 W. With the second sample we tried to pull less (29 A from each +12 V rail) for a total of approximately 785 W.

Of course we’d prefer the power supply shutting down instead of burning, but this should not be seen as a very negative point because in both cases we were overloading the unit a lot.

In both samples the components that burned were the +12 V rectifiers.