Topower PowerBird 900 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.
First we tested 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.
For the 100% load test we faced a small challenge. The +12V2 input from our load tester was exclusively connected to the power supply +12V2 rail through its EPS12V connector (+12V1 input was connected at the same time to the power supply +12V1, +12V3 and +12V6 rails), and the power supply over current protection circuit (OCP) wouldn’t allow us to pull more than 30.5 A from this rail, and we wanted it to be at 33 A, with +5 V and +3.3 V set at 12 A each. The difference from what we could actually configure and what we wanted to configure was very small, though.
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 | 7 A (84 W) | 12 A (144 W) | 19 A (228 W) | 26 A (312 W) | 33 A (396 W) |
| +12V2 | 7 A (84 W) | 12 A (144 W) | 19 A (228 W) | 26 A (312 W) | 30.5 A (366 W) |
| +5V | 2 A (10 W) | 6 A (30 W) | 8 A (40 W) | 10 A (50 W) | 15 A (75 W) |
| +3.3 V | 2 A (6.6 W) | 6 A (19.8 W) | 8 A (26.4 W) | 10 A (33 W) | 15 A (49.5 W) |
| +5VSB | 1 A (5 W) | 2 A (10 W0 | 2 A (10 W) | 3 A (15 W) | 3.5 A (17.5 W) |
| -12 V | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) |
| Total | 196.3 W | 354.1 W | 538.6 W | 726.1 W | 905.9 W |
| % Max Load | 21.8% | 39.3% | 59.8% | 80.7% | 100.7% |
| Room Temp. | 48.3° C | 48.0° C | 49.4° C | 46.9° C | 49.8° C |
| PSU Temp. | 48.5° C | 48.6° C | 49.7° C | 47.6° C | 53.0° C |
| Voltage Stability | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power (1) | 223 W | 395 W | 604 W | 837 W | 1,085 W |
| Efficiency (1) | 88.0% | 89.6% | 89.2% | 86.8% | 83.5% |
| AC Power (2) | 232.3 W | 413.5 W | 631.0 W | 868 W | 1,117 W |
| Efficiency (2) | 84.5% | 85.6% | 85.4% | 83.7% | 81.1% |
| AC Voltage | 112.3 V | 109.9 V | 108.1 V | 105.3 V | 102.3 V |
| Power Factor | 0.968 | 0.987 | 0.993 | 0.996 | 0.998 |
| Final Result | Pass | Pass | Pass | Pass | Pass |
Updated 06/24/2009: 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., 180 W), the active PFC circuit from this unit isn’t as good as when operating under higher loads, but 0.968 is still a good number.
PowerBird 900 W achieved efficiency above 85% when we pulled between 40% and 60% from its labeled wattage (i.e., between 360 W and 540 W). Under light load (20% load, i.e., 180 W) efficiency was still high, at 84.5%. At 80% load (720 W) efficiency was at 83.7%, which is a good number. At full load efficiency dropped to 81.1%, but still above the 80% mark.
Voltage stability was another highlight from PowerBird 900 W, with all voltages inside 3% of their nominal values(i.e., voltages were closer to their nominal value than needed, as ATX spec allows voltages to be up to 5% from their nominal values, 10% for -12 V). The -12 V output, however, was at -11.12 V during test number one, -11.29 V during test number two, -11.45 V during test number three and -11.60 V during test number four. These numbers are still inside the 10% margin allowed for this output, but we always like to see outputs as close as possible from their nominal values. During test number five this output was within 3% from its nominal value.
And finally we have noise and ripple, which were low all the time. Below you can see the results for test number five. As we always point out, the limits are 120 mV for +12 V and 50 mV for +5 V and +3.3 V and all numbers are peak-to-peak figures.
Figure 16: +12V1 input from load tester at 905.9 W (56.6 mV).
Figure 17: +12V2 input from load tester at 905.9 W (46.4 mV).
Figure 18: +5V rail with power supply delivering 905.9 W (15.8 mV).
Figure 19: +3.3 V rail with power supply delivering 905.9 W (21.2 mV).
Now let’s see if w
e could pull more than 900 W from this unit.