Antec EarthWatts 500 W Power Supply Review
Load Tests
Contents
We conducted several tests with this power supply, as described in the article Hardware Secrets Power Supply Test Methodology. All the tests described below were taken with a room temperature between 43° and 49.5° C. During our tests the power supply temperature was between 47° and 52° C.
Firs we t
ested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching how the reviewed unit behaved under each load. In the table below we list the load patterns we used and the results for each load.
+12V2 is the second +12V input of our load tester and on this test it was connected to the power supply EPS12V connector.
Since the power supply label states a 17 A limit for each rail and a 408 W maximum power for the +12 V output we kept these limits on our test number 5, so that’s why on this test you will see a current for +5 V and +3.3 V lines a little bit higher than what we would like to use. We, of course, pushed this power supply over its limits (the results are in the next page).
If you add all the power listed for each test, you may find a different value than what is posted under “Total” below. Since each output can vary slightly (e.g., the +5 V output working at +5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. On the “Total” row we are using the real amount of power being delivered, as measured by our load tester.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12V1 | 4 A (48 W) | 8 A (96 W) | 11 A (132 W) | 14 A (168 W) | 17 A (204 W) |
| +12V2 | 3 A (36 W) | 6 A (72 W) | 10 A (120 W) | 14 A (168 W) | 17 A (204 W) |
| +5V | 1 A (5 W) | 2 A (10 W) | 4 A (20 W) | 6 A (30 W) | 9 A (45 W) |
| +3.3 V | 1 A (3.3 W) | 2 A (6.6 W) | 4 A (13.2 W) | 6 A (19.8 W) | 9 A (29.7 W) |
| +5VSB | 1 A (5 W) | 1 A (5 W) | 1.5 A (7.5 W) | 2 A (10 W) | 2.5 A (12.5 W) |
| -12 V | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.8 W (9.6 W) |
| Total | 102 W | 193 W | 295 W | 396 W | 497 W |
| % Max Load | 20.4% | 38.6% | 59.0% | 79.2% | 99.4% |
| Result | Pass | Pass | Pass | Pass | Pass |
| Voltage Stability | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power (1) | 116 W | 220 W | 341 W | 468 W | 606 W |
| Efficiency (1) | 87.9% | 87.7% | 86.5% | 84.6% | 82.0% |
| AC Power (2) | 121.8 W | 227.3 W | 350.3 W | 480.6 W | 616.0 W |
| Efficiency (2) | 83.7% | 84.8% | 83.9% | 82.1% | 79.8% |
| AC Voltage | 111.6 V | 110.9 V | 109.7 V | 108.4 V | 106.4 V |
| PF | 0.988 | 0.992 | 0.996 | 0.997 | 0.998 |
| Final Result | Pass | Pass | Pass | Pass | Pass |
Updated 06/25/2009: We re-tested this power supply using our new GWInstek GPM-8212 power meter, which is a precision instrument and provides accuracy of 0.2% and thus presenting the correct readings for AC power and efficiency (results marked as "2" on the table above; results marked as "1" were measured with our previous power meter from Brand Electronics, which isn’t so precise as you can see). We also added the numbers for AC voltage during our tests, an important number as efficiency is directly proportional to AC voltage (the higher AC voltage is, the higher efficiency is). Also, manufacturers usually announce efficiency at 230 V, which usually inflates efficiency numbers. We added power factor (PF) numbers as well. These numbers measure the efficiency of the power supply active PFC circuit. This number should be as close to 1 as possible. Under light load (20% load, i.e., 100 W), the active PFC circuit from this unit isn’t as good as when operating under higher loads, but 0.988 is still an outstanding number.
EarthWatts 500 W could really deliver 500 W at 47° C as promised by Antec, with a very high efficiency around 84-85% if you pull up to 60% of its maximum capacity (i.e., up to 300 W). At 80% load (400 W) efficiency dropped to 82.1%, still a good number. But at full load efficiency was 0.2% short of 80%.
All voltages were really stable, inside a 3% limit from the nominal voltage – which is really great, as the limit is 5% –, except the -12 V output. This output was at -11.02 V, -11.16 V, -11.31 V, -11.45 V and -11.48 V. Even though ATX12V standard sets -12 V tolerance at 10% (which means it can go from -10.80 V to -13.20 V) we would like to see it closer to the nominal -12 V voltage.
We were really impressed by the very low level of electrical noise produced by this power supply, the lowest we’ve seen to date. Noise on +12V1 input was between 13 and 14.6 mV on tests 1, 2 and 3, increasing to 18 mV on test 4 and 23.2 mV on test 5, hundreds of miles away from the 120 mV limit. Noise on +5 V line was between 7.4 mV and 9 mV during our tests, also far away from its 50 mV limit. Noise on +3.3 V was also very low on tests 1 through 4 (between 6.2 mV and 7.8 mV) but increased a lot on test 5 (19.2 mV), probably because we had to increase the current on this line more than usual, as explained at the beginning of this page. All these numbers are peak-to-peak values. Below we show the noise level we found on the power supply outputs while the unit was operating at its full load (test number five).
Figure 14: Noise level at +12V1 input of the load tester.
Figure 15: Noise level at +12V2 input of the load tester.
Figure 16: Noise level at +5V input of the load tester.
Figure 17: Noise level at +3.3V input of the load tester.
