OCZ StealthXStream 400 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.
+12V1 and +12V2 are the two independent +12V inputs from our load tester and during our tests the +12V1 input was connected to the +12V1 rail the +12V2 input was connected to the +12V2 rail, so on this test +12V1 and +12V2 really represents the rails by the same name on the power supply.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12V1 | 2.5 A (30 W) | 5.5 A (66 W) | 8 A (96 W) | 10.5 A (126 W) | 14 A (168 W) |
| +12V2 | 2.5 A (30 W) | 5.5 A (66 W) | 8 A (96 W) | 10.5 A (126 W) | 13 A (156 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) | 2.5 A (12.5 W) |
| -12 V | 0.3 A (3.6 W) | 0.3 A (3.6 W) | 0.3 A (3.6 W) | 0.3 A (3.6 W) | 0.3 A (3.6 W) |
| Total | 77.4 W | 157.3 W | 236.1 W | 314.2 W | 402.7 W |
| % Max Load | 19.4% | 39.3% | 59.0% | 78.6% | 100.7% |
| Room Temp. | 45.6° C | 46.5° C | 46.1° C | 45.8° C | 47.2° C |
| PSU Temp. | 46.5° C | 47.5° C | 46.6° C | 47.1° C | 49.3° C |
| Voltage Stability | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power | 92.0 W | 184.4 W | 278.1 W | 376.0 W | 493.7 W |
| Efficiency | 84.1% | 85.3% | 84.9% | 83.6% | 81.6% |
| AC Voltage | 112.5 V | 112.4 V | 110.3 V | 109.7 V | 109.2 V |
| Power Factor | 0.982 | 0.99 | 0.995 | 0.997 | 0.998 |
| Final Result | Pass | Pass | Pass | Pass | Pass |
OCZ StealthXStream 400 W proved to be one of the best entry-level power supplies we’ve ever tested. It could not only deliver its labeled power at 47° C, but also presented high efficie
ncy, up to 85%. Usually when entry-level products are delivering their labeled wattage efficiency drops below 80%, but this simply didn’t happen with the reviewed power supply.
Voltage stability was another highlight from StealthXStream 400 W, with all outputs always within 3% from their nominal values, i.e., they were closer to their nominal values than required by ATX specification, which allows a tolerance of up to 5% for them. This includes the -12 V output, which traditionally doesn’t like to stay within this tighter limit.
Ripple and noise levels were always very low. Below you can see the results for test number five. The maximums allowed are 120 mV for +12 V and 50 mV for +5 V and +3.3 V. All values are peak-to-peak.
Figure 17: +12V1 rail with the power supply delivering 402.7 W (27.4 mV).
Figure 18: +12V2 rail with the power supply delivering 402.7 W (28.6 mV).
Figure 19: +5 V rail with the power supply delivering 402.7 W (11.6 mV).
Figure 20: +3.3 V rail with the power supply delivering 402.7 W (11.0 mV).
Now let’s see if we could pull more than 400 W from this unit.