Zalman ZM600-RS 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.
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.
The +12V1 and +12V2 inputs listed below are the two +12 V independent inputs from our load tester. During this test the +12V1 input was connected to the power supply +12V2 and +12V3 rails while the +12V2 input was connected to the power supply +12V1 rail.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12V1 | 4 A (48 W) | 9 A (108 W) | 13 A (156 W) | 17.5 A (210 W) | 21.5 A (258 W) |
| +12V2 | 4 A (48 W) | 9 A (108 W) | 13 A (156 W) | 17.5 A (210 W) | 21.5 A (258 W) |
| +5V | 1 A (5 W) | 2 A (10 W) | 4 A (20 W) | 6 A (30 W) | 8 A (40 W) |
| +3.3 V | 1 A (3.3 W) | 2 A (6.6 W) | 4 A (13.2 W) | 6 A (19.8 W) | 8 A (26.4 W) |
| +5VSB | 1 A (5 W) | 1 A (5 W) | 1.5 A (7.5 W) | 2 A (10 W) | 3 A (15 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 | 116.9 W | 246.9 W | 362.4 W | 489.2 W | 603.4 W |
| % Max Load | 19.5% | 41.2% | 60.4% | 81.5% | 100.6% |
| Room Temp. | 45.2° C | 44.4° C | 44.6° C | 46.0° C | 50.2° C |
| PSU Temp. | 50.1° C | 50.5° C | 51.2° C | 53.5° C | 58.4° C |
| Voltage Regulation | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Fail on -12 V | Fail on -12 V | Fail on -12 V |
| AC Power | 139.3 W | 286.2 W | 423.8 W | 584.8 W | 753.0 W |
| Efficiency | 83.9% | 86.3% | 85.5% | 83.7% | 80.1% |
| AC Voltage | 118.2 V | 116.9 | 115.3 V | 114.2 V | 112.8 V |
| Power Factor | 0.992 | 0.997 | 0.998 | 0.998 | 0.998 |
| Final Result | Pass | Pass | Pass | Pass | Pass |
Zalman ZM600-RS can really deliver its labeled wattage at high temperatures.
Efficiency was high when we pulled between 20% and 80% from its labeled wattage (i.e., between 120 W and 480 W), being between 83.7% and 86.3%. At full load (600 W) efficiency dropped to 80.1%, still above the 80% mark.
This unit is 80 Plus Bronze certified, meaning that it should present 82% efficiency at full load. This didn’t happen because differently from Ecos Consulting we test power supplies at high temperatures, and efficiency drops with temperature (read our Can We Trust the 80 Plus Certification? article for more details).
Voltages were always inside the allowed range.
This unit presented a noise level above the maximum allowed on its -12 V output during tests four and five. Usually we don’t “fail” the whole power supply when it presents noise out of range on its -12 V output. But you should note that noise at +12 V outputs was very high during test five, with the power supply almost touching the maximum allowed (120 mV). The maximum allowed for the +5 V and +3.3 V outputs is 50 mV. We saw this same high electrical noise problem with the 500 W version from this unit.
Figure 16: +12V1 input from load tester at 603.4 W (102.6 mV).
Figure 17: +12V2 input from load tester at 603.4 W (102.4 mV).
Figure 18: +5V rail with power supply delivering 603.4 W (34.2 mV).
Figure 19: +3.3 V rail with power supply delivering 603.4 W (25.4 mV).
When we tried to overload this power supply noise level at +12 V outputs was outside the maximum allowed value, and we only consider an overloading well succeeded if all parameters are within specs, which was not the case.