Nexus RX-8500 850 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.
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 +12V4 and +12V3 rails while the +12V2 input was connected to the power supply +12V2 rail.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12V1 | 6 A (72 W) | 13 A (156 W) | 20 A (240 W) | 25 A (300 W) | 31 A (372 W) |
| +12V2 | 6 A (72 W) | 12 A (144 W) | 17 A (204 W) | 25 A (300 W) | 31 A (372 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 (1 0 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 | 172.8 W | 347.3 W | 519.1 W | 697.1 W | 862.4 W |
| % Max Load | 20.3% | 40.9% | 61.1% | 82.0% | 101.5% |
| Room Temp. | 45.8° C | 45.1° C | 48.8° C | 47.3° C | 47.5° C |
| PSU Temp. | 47.3° C | 48.1° C | 51.0° C | 53.1° C | 53.2° C |
| Voltage Stability | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power | 211.1 W | 410.2 W | 617.7 W | 847.0 W | 1080.0 W |
| Efficiency | 81.9% | 84.7% | 84.0% | 82.3% | 79.9% |
| AC Voltage | 116.9 V | 114.6 V | 112.1 V | 109.4 V | 106.8 V |
| Power Factor | 0.963 | 0.986 | 0.981 | 0.982 | 0.976 |
| Final Result | Pass | Pass | Pass | Pass | Pass |
Nexus RX-8500 can really deliver 850 W at very high temperatures.
Efficiency was good but not outstanding. When we pulled between 40% and 60% from the power supply maximum capacity (between 340 W and 510 W) we saw efficiency between 84% and 84.7%. At light load (20%, i.e., 170 W) and 80% load (680 W) efficiency dropped to around 82%. And at full load efficiency was just at 79.9%.
Voltage regulation was a highlight from this product, with all voltages within 3% from their nominal values, i.e., voltages close to their nominal values that what is allowed (5%). This includes the -12 V output, which usually doesn’t like to stay so close to its nominal value, except when we pulled 850 W from this power supply (but this output was still inside the valid range).
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 15: +12V1 input from load tester at 862.4 W (35.2 mV).
Figure 16: +12V2 input from load tester at 862.4 W (38.4 mV).
Figure 17: +5V rail with power supply delivering 862.4 W (24.6 mV).
Figure 18: +3.3 V rail with power supply delivering 862.4 W (25.6 mV).
Now let’s see if we could pull more than 850 W from this unit.