Load Tests (Cont’d)

After these tests we tried to pull even more power from Antec EarthWatts 500 W. Below you can see the maximum amount of power we could extract from this unit keeping it working with its voltages and electrical noise level within the proper working range. During this test room temperature was of 46º C and the power supply was working at 47º C.

Here noise level increased just a little bit on the +12 V inputs, going to 26.2 mV on +12V1 and 25 mV on +12V2. These results are spectacular (the limit is 120 mV and any power supply capable of maintaining a noise level below 60 mV is a good product and we are talking about a power supply which noise level is almost five times lower than the limit). Noise on the other outputs remained the same.

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Figure 18: Noise level at +12V1 input of the load tester.

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Figure 19: Noise level at +12V2 input of the load tester.

We tried to pull even more power from the unit, but it wouldn’t turn on – showing us the over power protection (OPP) in action, which is great: it allows us to go over above the power supply limit but not high enough to the point where we would burn it.

On this unit over current protection (OCP) is disabled or is set at a value over 33 A. We made a simple test here, we set +12V1 at 5 A and then increased +12V2 to 33 A, and the power supply would work just fine. Since the label states a maximum current of 17 A per rail the power supply should not allow this.

Short circuit protection (SCP) worked fine for both +5 V and +12 V lines.

During our tests we could see the speed of the power supply fan changing as the power supply temperature increased. Below 30º C it spun slowly, making almost no noise, and after this temperature it started increasing its speed, which also increased noise level. But even with it running at full speed it didn’t make a lot of noise.

Another interesting thing about this power supply is that it runs really cool. In fact it gave us a lot of work to increase the temperature inside our “hot box”. Even running at full load we had to wait more than 15 minutes until our “hot box” reached our minimum working temperature of 45º C. With high-end power supplies we can heat our hot box in just a few minutes.

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