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 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.

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 it was connected to the power supply EPS12V – i.e. to the +12V1 rail. The +12V1 input was connected to the +12V2, +12V3 and +12V4 rails.

This power supply could deliver its rated power at 50º C – which would be perfect if noise level didn’t go out of spec at +5 V line after working for just one minute at this temperature.

Working at 45º C noise level at the +12V1 input from our load tester was at 49.4 mV, at the +12V2 input was at 36.8 mV, at the +5 V was at 23.2 mV and at the +3.3 V was at 28 mV. These are very good results. But after temperature increased to 50º C noise level started to increase after just one minute, jumping to 88 mV at the +12V1 input from our load tester (i.e. at the +12V2 rail from the power supply) and to 62.8 mV at the +5 V output, making the power supply to work out specs, as the maximum admissible noise level for this output is of 50 mV.

Not only that. Even at 45º C noise level at +5VSB was out of range, at 65.8 mV. This is the first time we’ve seen a power supply with such high noise level at this output.

Below you can compare what happened after working one minute at 50º C.

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Figure 18: +12V1 input from our load tester with power supply delivering 850 W at 45º C.

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Figure 19: +12V1 input from our load tester with power supply delivering 850 W after one minute at 50º C. See the big spikes.

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Figure 20: +5 V line with power supply delivering 850 W at 45º C.

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Figure 21: +5 V line with power supply delivering 850 W after one minute at 50º C. See the big spikes.

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Figure 22: Noise level at +5VSB was above 50 mV.

Taking out this “detail” it isn’t a bad power supply. It reached efficiency between 82.3% and 88.3%, staying always above 85% if you pull up to 80% of the power supply nominal power (i.e. up to 680 W).

Voltage regulation was excellent and during all our tests all outputs were within 3% of their nominal voltages – ATX specification defines that all outputs must be within 5% of their nominal voltages (10% for -12 V) –, except -12 V (this output was within the 10% tolerance set by ATX specification).

Let’s now see if we could pull even more power from this unit and our tests of the power supply protections.

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