Zalman ZM850-HP Plus 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 the behavior of the reviewed unit 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 powers listed for each test, you may find a different value than what is posted under “Total” below. Since each output can have a slight variation (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, the +12VA input was connected to the power supply +12V1, +12V2 and +12V3 rails, while the +12VB input was connected to the power supply +12V1 and +12V2 rails (EPS12V connector).
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12VA | 6 A (72 W) | 13 A (156 W) | 18.5 A (222 W) | 25 A (300 W) | 32 A (384 W) |
| +12VB | 6 A (72 W) | 12 A (144 W) | 18.5 A (222 W) | 25 A (300 W) | 32 A (384 W) |
| +5V | 2 A (10 W) | 4 A (20 W) | 6 A (30 W) | 8 A (40 W) | 10 A (50 W) |
| +3.3 V | 2 A (6.6 W) | 4 A (13.2 W) | 6 A (19.8 W) | 8 A (26.4 W) | 10 A (33 W) |
| +5VSB | 1 A (5 W) | 1.5 A (7.5 W) | 2 A (10 W) | 2.5 A (12.5 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 | 170.6 W | 342.4 W | 501.7 W | 670.7 W | 850.4 W |
| % Max Load | 20.1% | 40.3% | 59.0% | 78.9% | 100.0% |
| Room Temp. | 44.0° C | 44.5° C | 47.4° C | 46.4° C | 46.1° C |
| PSU Temp. | 46.8° C | 46.9° C | 47.6° C | 49.7° C | 51.2° C |
| Voltage Regulation | Pass | Pass | Pass | Failed at +3.3 V | Failed at +3.3 V |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power | 200.2 W | 393.8 W | 580.4 W | 791.0 W | 1029.0 W |
| Efficiency | 85.2% | 86.9% | 86.4% | 84.8% | 82.6% |
| AC Voltage | 113.8 V | 111.6 V | 110.5 V | 108.1 V | 104.2 V |
| Power Factor | 0.958 | 0.984 | 0.991 | 0.992 | 0.994 |
| Final Result | Pass | Pass | Pass | Fail | Fail |
The Zalman ZM850-HP Plus can really deliver its labeled wattage at high temperatures.
Efficiency was between 82.6% and 86.9% during our tests, a decent number but below what is promised by the 80 Plus Silver certification. We see this problem happening all the time: since data for the 80 Plus certification are collected at only 23° C, we see lots of products not being able to present the same efficiency level at high temperatures, since efficiency drops with temperature.
The positive voltages stayed within a tighter 3% regulation during tests one and two, but during test three the +3.3 V exited this tighter regulation, but was still within the proper range. During tests four and five, however, the +3.3 V output existed the proper range, at +3.12 V during test four and at +3.08 V during test five (the minimum allowed is +3.135 V), making this power supply to fail our tests.
Noise and ripple levels, on the other hand, were very low. Below you can see the results for the power supply outputs during test number five. The maximum allowed is 120 mV for the +12 V and -12 V outputs, and 50 mV for the +5 V, +3.3 V, and +5VSB outputs. All values are peak-to-peak figures.
Figure 17: +12VA input from load tester during test five at 850.4 W (37.2 mV)
Figure 18: +12VB input from load tester during test five at 850.4 W (45.6 mV)
Figure 19: +5V rail during test five at 850.4 W (14.8 mV)
Figure 20: +3.3 V rail during test five at 850.4 W (10.0 mV)
Let’s see if we can pull even more from the Zalman ZM850-HP Plus.