OCZ StealthXStream 600 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.
We connected the two ATX12V connectors from this power supply to the +12VB input from our load tester. This means that this input was connected to the +12V1 and +12V2 rails from the power supply. All other plugs were connected to the +12VA input from our load tester, meaning that this input was connected to the +12V3 and +12V4 rails from the power supply.
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.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12VA | 4 A (48 W) | 9 A (108 W) | 13 A (156 W) | 17.5 A (210 W) | 21.5 A (258 W) |
| +12VB | 4 A (48 W) | 9 A (108 W) | 13 A (156 W) | 17.5 A (210 W) | 21.5 A (258 W) |
| +5 V | 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 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 | 116.6 W | 245.4 W | 360.9 W | 486.4 W | 600.8 W |
| % Max Load | 19.4% | 40.9% | 60.2% | 81.1% | 100.1% |
| Room Temp. | 44.8° C | 44.3° C | 46.4° C | 48.4° C | 49.5° C |
| PSU Temp. | 50.6° C | 50.1° C | 52.1° C | 54.2° C | 58.9° C |
| Result | Pass | Pass | Pass | Pass | Pass |
| Voltage Stability | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power (1) | 138 W | 284 W | 423 W | 584 W | 749 W |
| Efficiency (1) | 84.9% | 86.8% | 85.7% | 83.8% | 80.8% |
| AC Power (2) | 144.8 W | 294.6 W | 435.4 W | 600.0 W | 764.0 W |
| Efficiency (2) | 80.5% | 83.3% | 82.9% | 81.1% | 78.6% |
| AC Voltage | 110.7 V | 109.8 V | 107.1 V | 106.8 V | 105.4 V |
| Power Factor | 0.983 | 0.993 | 0.997 | 0.998 | 0.998 |
Updated 01/22/2010: We re-tested this power supply using our new GWInsteak GPM-8212 power meter, which is a precision instrument and provides accuracy of 0.2% and thus presenting the correct readings for AC power and efficiency (results marked as "2&qu
ot; on the table above; results marked as "1" were measured with our previous power meter from Brand Electronics, which isn’t so precise as you can see). We also added the numbers for AC voltage during our tests, an important number as efficiency is directly proportional to AC voltage (the higher AC voltage is, the higher efficiency is). Also, manufacturers usually announce efficiency at 230 V, which usually inflates efficiency numbers. We added power factor (PF) numbers as well. These numbers measure the efficiency of the power supply active PFC circuit. This number should be as close to 1 as possible.
OCZ StealthXStream 600 W can really deliver its labeled power at 49.5° C, keeping efficiency above 80% if you pull up to 80% from its labeled wattage (i.e., up to 480 W) and presenting efficiency around 83% if you pull between 40% and 60% from its labeled maximum capacity (i.e., between 240 W and 360 W). These results are good for a power supply on this price range, but of course we would like to see a higher efficiency when the power supply delivered its full 600 W to keep the great results achieved on lighter loads.
Voltage regulation during all our tests (including the overload tests we will present in the next page) was outstanding, with all outputs within 3% of their nominal voltages – ATX specification defines that all outputs must be within 5% of their nominal voltages – including -12 V, which usually doesn’t like to stay within such tight tolerance.
Noise and ripple improved a lot when we got a second sample to re-test this power supply using our new precision power meter. When we were pulling 600 W from this power supply noise level at +12VA input from our load tester was at 23.8 mV (against 74 mV from the first sample), at +12VB input from our load tester was at 30.8 mV (against 64.6 mV from the first sample), at +5 V was 13.8 mV (against 25.4 mV from the first sample) and at +3.3 V was 18.6 mV (against 39.4 mV from the first sample), as you can see on the screenshots below (just to remember, the maximum allowed values are 120 mV for +12 V and 50 mV for +5 V and +3.3 V; all these values are peak-to-peak values).
Figure 15: Noise level at +12VA input from our load tester at 600 W.
Figure 16: Noise level at +12VB input from our load tester at 600 W.
Figure 17: Noise level at +5 V with power supply delivering 600 W.
Figure 18: Noise level at +3.3 V with power supply delivering 600 W.
Now let’s see if we could pull more power from this product.