iMicro PS-IM400WH 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.
Because we had no clue as to the real wattage of this power supply, we tested it differently. Starting from 85 W, we increased load little by little until we could see the maximum amount of power we could extract from the reviewed unit.
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. In the “Total” row, we are using the real amount of power being delivered, as measured by our load tester.
The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. During our tests, both were connected to the power supply’s single +12 V rail.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12VA | 3 A (36 W) | 3.5 A (42 W) | 4.5 A (54 W) | 5.5 A (66 W) | 6.25 A (75 W) |
| +12VB | 2.5 A (30 W) | 3.25 A (39 W) | 4 A (48 W) | 5 A (60 W) | 6 A (72 W) |
| +5V | 1 A (5 W) | 1 A (5 W) | 1.5 A (7.5 A) | 1.5 A (7.5 A) | 2 A (10 W) |
| +3.3 V | 1 A (5 W) | 1 A (5 W) | 1.5 A (4.95 W) | 1.5 A (4.95 W) | 2 A (6.6 W) |
| +5VSB | 1 A (5 W) | 1 A (5 W) | 1 A (5 W) | 1 A (5 W) | 1 A (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 | 78.2 W | 98.5 W | 128.6 W | 145.5 W | 169.5 W |
| % Max Load | 19.6% | 24.6% | 32.2% | 36.4% | 42.4% |
| Room Temp. | 41.3° C | 41.5° C | 41.9° C | 42.7° C | 43.4° C |
| PSU Temp. | 42.7° C | 43.5° C | 44.2° C | 44.4° C | 44.8° C |
| Voltage Regulation | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Fail on +3.3 V | Fail on +3.3 V | Fail on +3.3 V | Fail on +3.3 V and -12 V | Fail on +3.3 V and -12 V |
| AC Power | 102.1 W | 126.8 W | 164.7 W | 186.6 W | 218.6 W |
| Efficiency | 76.6% | 77.7% | 78.1% | 78.0% | 77.5% |
| AC Voltage | 110.1 V | 109.9 V | 110.2 V | 110.5 V | 110.4 V |
| Power Factor | 0.647 | 0.653 | 0.655 | 0.650 | 0.650 |
| Fina l Result |
Fail | Fail | Fail | Fail | Fail |
| Input | Test 6 | Test 7 | Test 8 | Test 9 | Test 10 |
| +12VA | 7.5 A (90 W) | 8.25 A (99 W) | 9.25 A (111 W) | 10 A (120 W) | 11 A (132 W) |
| +12VB | 7 A (84 W) | 8 A (96 W) | 9 A (108 W) | 10 A (120 W) | 11 A (132 W) |
| +5V | 2 A (10 W) | 2.5 A (12.5 W) | 2.5 A (12.5 W) | 3 A (15 W) | 3 A (15 W) |
| +3.3 V | 2 A (6.6 W) | 2.5 A (8.25 W) | 2.5 A (8.25 W) | 3 A (9.9 W) | 3 A (9.9 W) |
| +5VSB | 1 A (5 W) | 1 A (5 W) | 1 A (5 W) | 1 A (5 W) | 1 A (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 | 194.3 W | 217.5 W | 238.2 W | 260.4 W | 288.1 W |
| % Max Load | 48.6% | 54.4% | 59.6% | 65.1% | 72.0% |
| Room Temp. | 43.3° C | 45.0° C | 47.1° C | 49.0° C | 42.2° C |
| PSU Temp. | 44.8° C | 46.0° C | 47.8° C | 49.6° C | 48.5° C |
| Voltage Regulation | Pass | Pass | Fail on +12 V | Fail on +12 V | Fail on +12 V |
| Ripple and Noise | Fail on +3.3 V and -12 V | Fail on +5 V, +3.3 V, and -12 V | Fail on +5 V, +3.3 V, and -12 V | Fail on +12V, +5 V, +3.3 V, and -12 V | Fail on +12V, +5 V, +3.3 V, and -12 V |
| AC Power | 253.2 W | 287.3 W | 320.5 W | 358.2 W | 395.0 W |
| Efficiency | 76.7% | 75.7% | 74.3% | 72.7% | 72.9% |
| AC Voltage | 109.8 V | 109.0 V | 108.1 V | 107.6 V | 106.5 V |
| Power Factor | 0.647 | 0.645 | 0.645 | 0.652 | 0.653 |
| Final Result | Fail | Fail | Fail | Fail | Fail |
The iMicro PS-IM400WH isn’t a 400 W, as we suspected. In our tests it could deliver only up to 288 W. Above that, the power supply shuts down (at least it won’t burn or explode).
But carrying a fake wattage is the smallest of the problems presented by this power supply. It failed all our tests. The +12 V outputs presented voltages outside the proper range starting at 238 W, and because it lacks coils in its filtering stage, ripple and noise were always above the maximum allowed at the +3.3 V output during all tests. The -12 V output had noise and ripple levels above the maximum allowed starting at 145 W, the +5 V output presented noise above specs starting at 217 W, and the +12 V output presented noise above specs starting at 260 W.
During our test 10 noise level at +12 V output was at 131 mV, at +5 V output was at 58.8 mV, at +3.3 V output was at 57.2 mV, and at -12 V was at 185.4 mV.
Efficiency was always below 80%, between 72.9% and 78.1%.
