As usual we pushed this power supply over its official limits to see what happens.
First we tried to see if over current protection was active and at what level. To test this we removed all power supply cables from our load tester leaving only the main motherboard cable and increased current on +12V1 to 28 A. The power supply didn’t shut down. Since the label says that each +12 V rail has a limit of 22 A, the power supply should have shut down when we pulled 28 A. Since we could really see that each rail was physically connected to the monitoring integrated circuit in charge of OCP, we guess that OCP was set at a value that was higher than what was printed on the label. We could keep increasing the current on +12V1 but +12 V voltage started dropping.
Our next move was to discover what was the maximum amount of power this unit can deliver still working inside its specs.
Starting from pattern number six (see previous page) we increased current on both +12 V rails to 24 A and current on +5 V and +3.3 V rails to 10 A each. With this pattern we were pulling 681.2 W from the unit but voltages were outside specs – voltage on +12V1 was at 10 V, for example. Under voltage protection (UVP) didn’t enter in action like it should, so it is either disabled (which we don’t think it is the case as the monitoring chip supports this feature) or it is configured to enter in action only when voltages are too far away from their nominal values (which is more probable).
Then we configured both +12V1 and +12V2 rails to pull 22 A, keeping +5 V and +3.3 V at 10 A. At this configuration the power supply was delivering 617 W and we were pulling 852 W from the wall, so efficiency was at 72.4%. After two minutes working at this configuration the power supply shut down, so one of its protections entered in action.
So we decreased current on +12V1 and +12V2 to 21 A, making the power supply to deliver 596 W and pull 819 W from the power grid – so efficiency was at 72.8%. The problem was that after one and a half minutes under this configuration the power supply silently died. After opening the power supply and testing all its major components we could see that the +12 V rectifier burned.
Enermax says that this product has over power protection (OPP or OLP; both acronyms mean the same thing), however the monitoring integrated circuit does not provide this feature. If this power supply really has this feature implemented outside this chip (which doesn’t seem to be the case), it is configured at a value that is too high and that we couldn’t see it in action.
Because the power supply burned so fast we couldn’t check noise level for all outputs (we could only see for +12V1, which was at 47 mV).
So we couldn’t determine if power supply can deliver more than 500 W continuously.
Short circuit protection (SCP) worked fine for both +5 V and +12 V lines.
When the power supply fan is running slowly it is really quiet, but as soon as it starts spinning at its full speed noise level becomes very high.