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 +12V2 input from our load tester with a low current (1 A) and increased current on +12V1 input (which was connected to the power supply +12V1 rail) until the power shut down. This happened only when we tried to pull more than 32 A, a value that is too far from the labeled 22 A limit that each +12 V rail has in theory. Investigating further this question we discovered that the power supply was shutting down not because of OCP, but because of over voltage protection (OVP). When we tried pulling 32.7 A from the +12V1 rail, ripple was at 840 mV, making voltages to be completely out of range and thus activating this other protection.
So at least with us over current protection was either disabled or configured at a value that was too high, making this power supply to operate as a single rail power supply (the difference between single rail and multi rail power supplies is the addition of multiple over current protection circuits on the later).
When we configured our load tester to pull more than 600 W we had the issue described on previous page – the power supply wouldn’t turn on, only if we first selected a lighter load first and then move to the heavier load.
The maximum amount of power we could pull from Rosewill RD600N-2SB-SL-BK with it still working inside ATX specs can be found below. At this configuration noise level was very high, around 100 mV at +12V1 and +12V2, with noise level at -12 V touching 120 mV.
Input
Maximum
+12V1
22 A (264 W)
+12V2
22 A (264 W)
+5V
16 A (80 W)
+3.3 V
16 A (52.8 W)
+5VSB
2.5 A (12.5 W)
-12 V
0.5 A (6 W)
Total
675 W
% Max Load
112.5%
Room Temp.
42.6º C
PSU Temp.
46.5º C
Load Test
Pass
Voltage Stability
Pass
Ripple and Noise
Pass
AC Power
864 W
Efficiency
78.1%
Final Result
Pass
Short circuit protection (SCP) worked fine for both +5 V and +12 V lines.
