Load Testing
As some of you may know, my load tester failed (more specifically, the rail select switch on the oscilloscope output melted) after reviewing the Bliss 600W power supply. Now, one month and hundreds of dollars later, I have a new load tester, with increased loading capacity (up to 1.3KW) and smaller increments on some rails (5A on the 3.3V rail and 0.5A on the 5Vsb rail, as opposed to 10A and 1A respectively on the old load tester). As a result, Test 1 is now done with the minimum load on all rails (about 70W in total), and Test 2 is what Test 1 used to be.
Test 1 (70.64W Load – Cold)
| Rail |
Load |
Voltage |
Ripple |
| 12V |
2.3A |
12.04V |
5.8mV |
| 5V |
5.03A |
5.03V |
4.2mV |
| 3.3V |
4.93A |
3.35V |
4.0mV |
| -12V |
0.1A |
-11.69V |
7.2mV |
| 5Vsb |
1.01A |
5.03V |
6.8mV |
| AC Power |
90.6W |
| Efficiency |
77.96% |
| Power Factor |
0.88 |
.
Test 2 (125.44W Load – Cold)
| Rail |
Load |
Voltage |
Ripple |
| 12V |
6.9A |
11.94V |
6.2mV |
| 5V |
5.04A |
5.04V |
4.4mV |
| 3.3V |
4.93A |
3.35V |
4.4mV |
| -12V |
0.1A |
-11.72V |
7.2mV |
| 5Vsb |
1.0A |
5.02V |
7.4mV |
| AC Power |
151.9W |
| Efficiency |
82.58% |
| Power Factor |
0.97 |
.
Test 3 (197.06W Load – Cold)
| Rail |
Load |
Voltage |
Ripple |
| 12V |
9.4A |
12.07V |
7.4mV |
| 5V |
9.9A |
4.95V |
5.4mV |
| 3.3V |
10.06A |
3.32V |
5.2mV |
| -12V |
0.1A |
-11.96V |
8.8mV |
| 5Vsb |
1.0A |
4.98V |
12.2mV |
| AC Power |
236.3W |
| Efficiency |
83.39% |
| Power Factor |
0.98 |
.
Test 4 (250.84W Load – Cold)
| Rail |
Load |
Voltage |
Ripple |
| 12V |
14.0A |
11.96V |
23.8mV |
| 5V |
9.92A |
4.96V |
6.2mV |
| 3.3V |
10.0A |
3.3V |
7.2mV |
| -12V |
0.1A |
-12.0V |
8.8mV |
| 5Vsb |
0.99A |
4.96A |
14.2mV |
| AC Power |
300.0W |
| Efficiency |
83.61% |
| Power Factor |
0.97 |
.
Test 5 (302.8W Load – Cold)
| Rail |
Load |
Voltage |
Ripple |
| 12V |
18.5A |
11.87V |
10.8mV |
| 5V |
9.92A |
4.96V |
6.2mV |
| 3.3V |
9.97A |
3.29V |
9.4mV |
| -12V |
0.1A |
-12.03V |
10.0mV |
| 5Vsb |
0.99A |
4.95V |
15.4mV |
| AC Power |
362.1W |
| Efficiency |
83.62% |
| Power Factor |
0.97 |
.
Test 6 (352.77W Load – Cold)
| Rail |
Load |
Voltage |
Ripple |
| 12V |
22.83A |
11.8V |
12.4mV |
| 5V |
9.94A |
4.97V |
7.2mV |
| 3.3V |
9.97A |
3.29V |
10.4mV |
| -12V |
0.1A |
-12.07V |
12.0mV |
| 5Vsb |
0.99A |
4.95V |
17.4mV |
| AC Power |
426W |
| Efficiency |
82.81% |
| Power Factor |
0.99 |
.
Test 7 (401.71W Load – Cold)
| Rail |
Load |
Voltage |
Ripple |
| 12V |
27.1A |
11.73V |
13.8mV |
| 5V |
9.98A |
4.99V |
8.6mV |
| 3.3V |
9.97A |
3.29V |
12.6mV |
| -12V |
0.1A |
-12.11V |
14.4mV |
| 5Vsb |
0.99A |
4.94V |
18.6mV |
| AC Power |
491.8W |
| Efficiency |
81.68% |
| Power Factor |
0.99 |
.
Test 8 (458.76W Load – Cold)
| Rail |
Load |
Voltage |
Ripple |
| 12V |
29.6A |
11.85V |
18.8mV |
| 5V |
14.79A |
4.93V |
9.2mV |
| 3.3V |
9.94A |
3.28V |
13.0mV |
| -12V |
0.2A |
-12.21V |
22.4mV |
| 5Vsb |
1.47A |
4.9V |
16.0mV |
| AC Power |
574.1W |
| Efficiency |
79.91% |
| Power Factor |
0.98 |
.
Overload Test (498.83W Load – Cold)
| Rail |
Load |
Voltage |
Ripple |
| 12V |
31.8A |
11.82V |
23.2mV |
| 5V |
14.76A |
4.92V |
11.0mV |
| 3.3V |
14.67A |
3.26V |
13.0mV |
| -12V |
0.2A |
-12.25V |
26.4mV |
| 5Vsb |
1.46A |
4.88V |
17.6mV |
| AC Power |
632.8W |
| Efficiency |
78.83% |
| Power Factor |
0.98 |
.
Starting with the 12V rail, The voltage was off by 0.27V at most (Test 7), which gives us 2.25% regulation. Its highest value was 12.07V during Test 3. This gives us a total variation of 0.34V, or 2.83%. The 5V rail had maximum and minimum values of 5.04V and 4.93V respectively. At worst, this is off by 0.07V, or 1.4%, and the variation is 0.11V, or 2.2%. The 3.3V rail was of by 0.05V, or 1.52% at most, and dropped by 0.07V, or 2.12%. While this result is certainly acceptable, I would prefer to see less variation than this as the load changes.
The VS450 was just barely able to maintain 80plus standard efficiency levels throughout the testing. Under 70W (15%) Load, the efficiency was only at about 78%, but it climbed considerably to over 82% at 28% load. Although I didn’t test it at 20% load (80plus’s lowest load level) it’s a fair assumption that it would have been about 80% at that load level. The efficiency peaked at 83.62% during Test 5 at 300W load, and at full load, it was just a hair under 80%, but I’m willing to let that one slide, as my equipment isn’t quite as precise as 80plus’s. Bear in mind, however that the VS450 is not 80plus certified, and wouldn’t be able to maintain this efficiency if used with a lower input voltage.
I was able to overload the power supply to 500W. During this test, the voltages were still within acceptable ranges, but the efficiency was below 80%.
| Rail |
Test 8 (458.76W) |
Overload Test (498.83W) |
| 12V |
 |
 |
| 5V |
 |
 |
| 3.3V |
 |
 |
| -12V |
 |
 |
| 5Vsb |
 |
 |
.
The ripple was very well suppressed. In fact, below 250W load, most of the rails had single digit ripple figures. A few spikes started to show up on the 12V rail during test 4, pushing the ripple to just over 20mV, but they disappeared during subsequent tests. The 12V ripple didn’t come back up above the 20mV mark again until the overload test. On all of the other rails except for the -12V, the ripple stayed under 20mV at all times, which is an excellent result.
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