Before overloading the power supply we always test to see if the over current protection (OCP) circuit is active and at what level it is configured.
To test this we configured our load tester to pull only 1 A from its +12V1 input and 33 A from its +12V2 input, which was connected to the power supply EPS12V connector. Under this scenario the power supply should have shut down, what didn’t happen, showing that this unit does not feature over current protection. In fact if it doesn’t have OCP circuit, this means that its +12 V rails are not independent and this power supply in fact uses a single rail design. The difference between single rail and multiple rail design is the use of individual OCP circuits for each rail on the latter (click here to learn more about this).
Then starting from test number five shown on previous page, we started increasing currents on the two +12 V inputs from our load tester. If we tried to pull more than 29 A on each input the power supply shut down, showing that one of its protections entered in action, which is terrific.
The maximum we could pull from this unit is summarized on the table below.
Input | Maximum |
+12V1 | 29 A (348 W) |
+12V2 | 29 A (348 W) |
+5V | 10 A (50 W) |
+3.3 V | 10 A (33 W) |
+5VSB | 2.2 A (11 W) |
-12 V | 0.5 A (6 W) |
Total | 776.9 W |
% Max Load | 111.0% |
Room Temp. | 48.7º C |
PSU Temp. | 52.5º C |
AC Power | 1050 W |
Efficiency | 74% |
Ripple and noise were still very low, at 44.4 mV on the +12V1 input from our load tester and at 34.4 mV on the +5 V input from our load tester.
As you can see, efficiency stayed on the same level as when we were pulling 700 W from this unit.
Short circuit protection (SCP) worked fine for both +5 V and +12 V lines.
In summary, you won’t burn or explode this unit if you try to pull more than it is capable of.
