Scythe Kamariki 4 550 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 out tests the +12V1 input was connected to the power supply +12V1 rail and +12V2 input was connected to the power supply +12V2 rail.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12V1 | 4 A (48 W) | 8 A (96 W) | 12 A (144 W) | 16 A (192 W) | 20 A (240 W) |
| +12V2 | 4 A (48 W) | 8 A (96 W) | 12 A (144 W) | 16 A (192 W) | 20 A (240 W) |
| +5V | 1 A (5 W) | 2 A (10 W) | 4 A (20 W) | 5 A (25 W) | 6 A (30 W) |
| +3.3 V | 1 A (3.3 W) | 2 A (6.6 W) | 4 A (13.2 W) | 5 A (16.5 W) | 6 A (19.8 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 | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) |
| Total | 116.3 W | 220.8 W | 335.8 W | 439.9 W | 542.6 W |
| % Max Load | 21.1% | 40.1% | 61.1% | 80.0% | 98.7% |
| Room Temp. | 46.2° C | 44.9° C | 46.5° C | 47.6° C | 45.1° C |
| PSU Temp. | 50.9° C | 51.0° C | 50.6° C | 52.0° C | 54.4° C |
| Voltage Stability | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power | 145.1 W | 265.0 W | 403.5 W | 536.4 W | 677.0 W |
| Efficiency | 80.2% | 83.3% | 83.2% | 82.0% | 80.1% |
| AC Voltage | 113.3 V | 112.7 V | 110.8 V | 110.3 V | 107.3 V |
| Power Factor | 0.927 | 0.965 | 0.981 | 0.988 | 0.991 |
| Final Result | Pass | Pass | Pass | Pass | Pass |
Scythe Kamariki 4 550 W can really deliver its labeled power at 45° C, which is great.
Efficiency was good, but not spectacular. Typically between 82% and 83% makes Kamariki 4 to be a decent but not outstanding product. At light load (20% load, i.e., 110 W) and full load (550 W) efficiency was at 80%.
Voltage stability was the highlight of this product, with all of them (including the -12 V output, which usually don’t like to stay close to its nominal voltage) within 3% of their nominal values. Translation: voltages closer to their nominal value than demanded by the ATX specification, which gives a 5% tolerance for all outputs (10% for -12 V).
Ripple and noise levels were low. Below you can see the screenshots from test number five, with this power supply delivering 550 W. Just to remember, the maximum allowed for the +12 V outputs is 120 mV and the maximum allowed for the +5 V and +3.3 V outputs is 50 mV. All these values are peak-to-peak figures.
Figure 15: +12V1 input from load tester at 542.6 W (58.6 mV).
Figure 16: +12V2 input from load tester at 548.6 W (58.6 mV).
Figure 17: +5V rail with power supply delivering 548.6 W (34.8 mV).
Figure 18: +3.3 V rail with power supply delivering 548.6 W (31.4 mV).
Even though this won’t make any difference for the user, notice how power factor was at 0.927 during test one, and usually power supplies with active PFC present a power factor of at least 0.98.
Now let’s see if we could pull even more power from Kamariki 4 550 W.