SilverStone ST45SF-G 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 the behavior of the reviewed unit 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 powers listed for each test, you may find a different value than what is posted under “Total” below. Since each output can have a slight variation (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. In the “Total” row, we are using the real amount of power being delivered, as measured by our load tester.
The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. During this test, the +12VA and +12VB inputs were connected to the power supply’s single +1
2 V rail. (The +12VB input was connected to the power supply EPS12V connector.)
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12VA | 3 A (36 W) | 6 A (72 W) | 9 A (108 W) | 12.5 A (150 W) | 15.5 A (186 W) |
| +12VB | 3 A (36 W) | 6 A (72 W) | 9 A (108 W) | 12.5 A (150 W) | 15 A (180 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) | 1.5 A (7.5 W) | 2 A (10 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 | 91.7 W | 172.2 W | 260.2 W | 361.4 W | 449.8 W |
| % Max Load | 20.4% | 38.3% | 57.8% | 80.3% | 100.0% |
| Room Temp. | 43.6° C | 43.2° C | 42.8° C | 43.2° C | 45.4° C |
| PSU Temp. | 47.8° C | 46.7° C | 46.2° C | 46.5° C | 49.8° C |
| Voltage Regulation | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power | 106.0 W | 192.5 W | 291.0 W | 414.2 W | 525.3 W |
| Efficiency | 86.5% | 89.5% | 89.4% | 87.3% | 85.6% |
| AC Voltage | 117.2 V | 116.8 V | 115.4 V | 114.6 V | 113.9 V |
| Power Factor | 0.969 | 0.970 | 0.978 | 0.986 | 0.989 |
| Final Result | Pass | Pass | Pass | Pass | Pass |
The 80 Plus Gold certification guarantees minimum efficiencies of 87% at 20% load, 90% at 50% load, and 87% at 100% load. In our tests, the SilverStone ST45SF-G presented 86.5% efficiency at 20% load. We didn’t test this power supply at 50% load, but considering that we saw 89.5% efficiency at 40% load and 89.4% efficiency at 60% load, we can assume that this unit is able to achieve 90% efficiency at 50% load. At full load, we saw 85.6% efficiency, which is below the minimum advertised by the 80 Plus Gold certification. We tested two samples of this power supply, and with the other sample, efficiency at full load was at 84.9 percent. Keep in mind that we tested this power supply between 42° C and 45° C, while the 80 Plus tests are conducted at 23° C, and efficiency drops as temperature increases.
Voltage regulation varied a bit between the two samples we tested. With one of the samples, all positive voltages were within 3% of their nominal values, which is what we want to see. With the second sample, however, voltages were sometimes outside this tighter range but still inside the allowed margin. See table below. The ATX12V specification states that positive voltages must be within 5% of their nominal values, and negative voltages must be within 10% of their nominal values.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12VA | ≤ 3% | ≤ 3% | ≤ 3% | ≤ 3% | ≤ 3% |
| +12VB | ≤ 3% | ≤ 3% | ≤ 3% | ≤ 3% | ≤ 3% |
| +5 V | ≤ 3% | ≤ 3% | ≤ 3% | ≤ 3% | ≤ 3% |
| +3.3 V | ≤ 3% | ≤ 3% | ≤ 3% | +3.18 V | +3.14 V |
| +5VSB | ≤ 3% | ≤ 3% | ≤ 3% | +4.82 V | +4.78 V |
| -12 V | -11.24 V | -11.34 V | -11.47 V | ≤ 3% | ≤ 3% |
Let’s discuss the ripple and noise levels on the next page.