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 do this we installed one auxiliary video card power cable from the modular cabling system to the +12V2 input from our load tester and removed the auxiliary video card power cable that was installed to the +12V1 input from our load tester. This way we had only +12V1 rail from the power supply connected to our load tester.
Under this configuration the power supply should shut down if we pulled too much current. The power supply label states a 40 A limit for each rail. We configured our load tester to pull 33 A from the motherboard main cable and EPS12V cable plus another 33 A from the auxiliary video card cable for a total of 66 A being pulled from HX1000W’s +12V1 rail, but the power supply didn’t shut down.
This means that either the over current circuit is disabled or it is configured at a value above 66 A. We couldn’t pull more than that due to a limitation of our load tester.
On the other hand the power supply worked fine under this extreme condition. Unfortunately we were limited by our equipment. Otherwise we’d like to try pulling 66 A from +12V2 at the same time to see what would happen. If the power supply survived, it would show us that we were facing a model capable of delivering at least 1,500 W on its +12V outputs, plus what it could deliver on the other outputs (+5 V, +3.3 V, +5VSB and -12 V).
With our original cable configuration (as describe on previous page) we started increasing current to see what would happen. But this test wasn’t fair: since we had already maxed out the +12 V outputs, we could only increase current on +5 V and +3.3 V, which isn’t our preferred way of overloading a power supply because, as we explained before, we are more concerned about how much current/power the +12 V outputs can deliver.
From test number five we increased current on +5 V and +3.3 V to 30 A each. Under this configuration we were pulling 1,039 W from the power supply at 47º C. We probably could pull more from this power supply if we weren’t limited by our equipment, so we couldn’t measure the real maximum power HX1000W can deliver.
We are very confident that HX1000W is really a 1,500 W power supply – since it is internally identical to Thermaltake Toughpower 1,500 W – but Corsair decided to label it as a 1,000 W model because of efficiency: pulling more than 1,000 W efficiency will probably drop below the 80% mark and if Corsair labeled this unit as an 1,100 W unit or even an 1,200 W it couldn’t guaranteed a minimum 80% efficiency at full load and it wouldn’t be able to get the “80 Plus” certification.
