Load Tests

We made several tests with this power supply as described in the article Hardware Secrets Power Supply Test Methodology.

First we tested this power supply with five different loads patterns, trying to pull around 20%, 40%, 60%, 80% and 100% of its labeled maximum capacity (under “% Max Load” we list the actual percentage that was used), watching how the reviewed unit behaved under each load. On the table below we list the load patterns we used and the results for each load. This was the same configuration we used with other 500 W power supplies we’ve reviewed recently, like Antec EarthWatts 500 W and Enermax Liberty DXX 500 W.

For the 100% load test we used two patterns. On the first one, test number five, we respected the maximum combined limit for the two +12 V rails printed on the power supply box (29 A or 348 W). In order to respect this limit, however, we were testing the power supply with more current on the +5 V and +3.3 V lines than we wanted. So we included a sixth pattern also pulling 500 W from Strider ST50F but pulling more current from +12 V and less current from +5 V and +3.3 V, using the same pattern used on the tests of the two abovementioned power supplies.

If you add all the powers listed for each test you may find a value different from what posted under “Total” below. Since each output can have a slight variation (e.g. +5 V output working at 5.10 V) the actual total amount of power being delivered is slightly different from the calculated value. On “Total” row we are using the real amount of power being delivered, as measured by our load tester.

+12V2 is the second +12V input from our load tester and during our tests we connected the power supply EPS12V connector to it. Keep in mind that the EPS12V connector is half connected to the power supply +12V1 rail and half to the +12V2 rail. The video card auxiliary power plug, which is connected to the power supply +12V2 rail, was connected on the +12V1 input from our load tester.

The good news is that this power supply can really deliver 500 W at a room temperature of 50º C on both patterns we used for 100% load (tests five and six).

But, as you know if you read our power supply reviews, power isn’t everything.

This power supply provided an outstanding efficiency above 85% when we pulled up to 60% of the power supply maximum labeled capacity (i.e. up to 300 W) and 84% when we pulled 80% of the power supply official maximum capacity (400 W). But when we pulled 500 W from this power supply we got two results. Using pattern five, where we pulled less power from +12 V and more power from +5 V and +3.3 V, efficiency was at 80.6% – not bad, but could be better, especially when we saw efficiency over 85% on other patterns. But using pattern six, where we pulled more power from +12 V and less power from +5 V and +3.3 V, efficiency increased to 82.1%.

On efficiency this power supply was far better than Enermax Liberty DXX 500 W (which efficiency was between 76.1% and 82.5%), but Antec EarthWatts 500 W and Corsair VX450W (which is the same power supply as Antec EarthWatts 500 W but with a different housing) achieved a little bit better efficiency.

Voltage regulation during all our tests (including the overload tests we will present on next page) was excellent, with all outputs within 3% of their nominal voltages – ATX specification defines that all outputs must be within 5% of their nominal voltages – except on -12 V, which was between -11.10 V and -11.43 V in all our tests. These numbers, however, are still inside the 10% margin that is set by the ATX spec for this output. Of course we always want to see values closer to the nominal voltage.

This power supply achieved low ripple and noise levels, but Antec EarthWatts 500 W, Corsair VX450W and Enermax Liberty DXX 500 W achieved lower levels here. During our test number five – i.e. with the power supply delivering 500 W – noise level at +12V1 input from our load tester was at 56 mV, noise level at +12V2 input from our load tester was at 46.6 mV, noise level at +5 V was at 23.6 mV and noise level at +3.3 V was at 26.5 mV. With pattern number six the results were similar. Just to remember, all values are peak-to-peak voltages and the maximum allowed set by ATX standard is 120 mV for +12 V and 50 mV for +5 V and +3.3 V.

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Figure 19: Noise level at +12V1 input from our load tester with power supply delivering 500 W.

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Figure 20: Noise level at +12V2 from our load tester with power supply delivering 500 W.

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Figure 21: Noise level at +5 V with power supply delivering 500 W.

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Figure 22: Noise level at +3.3 V with power supply delivering 500 W.

The noise at -12 V output, however, was at a very high level. It is common for the -12 V output to achieve a noise level far above +12 V output, but so far we haven’t seen anything like this. During patterns one thru four, noise level at this output was between 50 mV and 53 mV, but when we were pulling 500 W it jumped to 93.6 mV. This reflects the current increase from 0.5 A to 0.8 A on this output and the use of a very thin 24 AWG wire on this output didn’t make things easy.

Let’s now see if we could pull more power from this product.

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