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 (main motherboard and peripheral connectors) and +12V2 (video card power connector) rails, while the +12V2 input was connected to the +12V2 (EPS12V connector) rail.
Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
+12V1 | 5 A (60 W) | 9 A (108 W) | 14 A (168 W) | 19 A (228 W) | 24 A (288 W) |
+12V2 | 4 A (48 W) | 9 A (108 W) | 14 A (168 W) | 18 A (216 W) | 23 A (276 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 | 128.4 W | 244.8 W | 382.3 W | 500.4 W | 628.7 W |
% Max Load | 20.7% | 39.5% | 61.7% | 80.7% | 101.4% |
Room Temp. | 44.5º C | 45.6º C | 48.0º C | 49.5º C | 45.5º C |
PSU Temp. | 45.5º C | 46.6º C | 49.9º C | 52.7º C | 48.4º C |
Voltage Stability | Pass | Pass | Pass | Pass | Pass |
Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
AC Power | 161.6 W | 295.0 W | 462.8 W | 619.0 W | 795.0 W |
Efficiency | 79.5% | 83.0% | 82.6% | 80.8% | 79.1% |
AC Voltage | 112.6 V | 110.2 V | 109.7 V | 107.8 V | 105.3 V |
Power Factor | 0.977 | 0.99 | 0.995 | 0.996 | 0.996 |
Final Result | Pass | Pass | Pass | Pass | Pass |
Before commenting our results, we must say that the first SY-620PAF sample we got burned when we tried to pull 620 W from it (test number five) and after inspecting it we found out that one of the +12 V rectifiers was the component that burned. We replaced it and the same thing happened again. We got a second sample, which worked just fine, so our first sample was defective. The results above are from this second sample.
Seventeam ST-620PAF presents decent efficiency around 83% when we pulled between 40% and 60% from its labeled power (between 248 W and 372 W). At 80% load (496 W) efficiency dropped to 80.8%, still above 80%. But at light load (20% load, i.e., 124 W) and full load (620 W) efficiency dropped below the 80% mark.
This unit is 80 Plus certified, but you have to keep in mind that they test power supplies at a room temperature of 23º C (which is impossible to be achieved inside a PC), while we test them at a room temperature at least the double. The higher the temperature, the lower efficiency is.
Voltage stability was the highlight from this product. All voltages (including -12 V) were within 3% from their nominal value, whereas the ATX specification says they must be within 5%. Translation: voltages were closer to their nominal values than needed.
Ripple and noise levels were extremely low except on -12 V output, where they were always high (from 96.0 mV during test one to 108.2 mV during test five), but still inside the maximum allowed. You can see the results for test number five below. All numbers are peak-to-peak figures and the maximum allowed is 120 mV for the +12 V outputs and 50 mV for the +3.3 V and +5 V outputs.
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Figure 14: +12V1 input from load tester at 628.7 W (40.6 mV).
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Figure 15: +12V2 input from load tester at 628.7 W (48.2 mV).
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Figure 16: +5V rail with power supply delivering 628.7 W (17.2 mV).
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Figure 17: +3.3 V rail with power supply delivering 628.7 W (16.2 mV).
Let’s see if we could pull more than 620 W from this unit.
