Why you can trust Tom's Hardware Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.
Load Regulation, Hold-Up Time, And Inrush Current
To learn more about our PSU tests and methodology, please check out How We Test Power Supply Units.
Primary Rails And 5VSB Load Regulation
Load Regulation testing is detailed here.
Hold-Up Time
Our hold-up time tests are described in detail here.
Not only does the measured hold-up time fall short of 17ms, but to make matters worse the power-good signal lasts longer. That means it's inaccurate, since the rails are already out of spec by the time it drops. This is a great shame for such an expensive PSU. We could forgive a slightly lower-than-required hold-up time, but we never tolerate fake power-good signals.
Inrush Current
For details on our inrush current testing, please click here.
The inrush current is relatively low with both voltage inputs.
Load Regulation And Efficiency Measurements
The first set of tests reveals the stability of the voltage rails and the ST1200-PT's efficiency. The applied load equals (approximately) 10 to 110 percent of the PSU's maximum load in increments of 10 percentage points.
We conducted two additional tests. During the first, we stressed the two minor rails (5V and 3.3V) with a high load, while the load at +12V was only 0.1A. This test reveals whether a PSU is Haswell-ready or not. In the second test, we determined the maximum load the +12V rail could handle with minimal load on the minor rails.
| Test # | 12V | 5V | 3.3V | 5VSB | DC/AC (Watts) | Efficiency | Fan Speed | Fan Noise | Temps (In/Out) | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 8.087A | 1.995A | 1.975A | 1.001A | 119.79 | 84.21% | 0 RPM | 0 dB(A) | 44.89°C | 0.942 |
| 12.145V | 5.008V | 3.336V | 4.989V | 142.25 | 41.78°C | 115.1V | ||||
| 2 | 17.206A | 3.000A | 2.974A | 1.206A | 239.61 | 89.79% | 2140 RPM | 52.2 dB(A) | 41.37°C | 0.968 |
| 12.132V | 4.992V | 3.325V | 4.975V | 266.86 | 43.79°C | 115.1V | ||||
| 3 | 26.733A | 3.511A | 3.498A | 1.410A | 359.85 | 91.23% | 2155 RPM | 52.3 dB(A) | 41.88°C | 0.979 |
| 12.112V | 4.977V | 3.314V | 4.960V | 394.45 | 44.67°C | 115.1V | ||||
| 4 | 36.250A | 4.025A | 3.990A | 1.616A | 479.62 | 91.53% | 2180 RPM | 52.7dB(A) | 42.05°C | 0.985 |
| 12.095V | 4.967V | 3.305V | 4.946V | 524.03 | 45.84°C | 115.1V | ||||
| 5 | 45.465A | 5.041A | 5.002A | 1.821A | 599.54 | 91.35% | 2260 RPM | 54.5 dB(A) | 42.86°C | 0.988 |
| 12.077V | 4.955V | 3.298V | 4.935V | 656.34 | 47.37°C | 115.3V | ||||
| 6 | 54.708A | 6.068A | 6.016A | 2.030A | 719.51 | 90.38% | 2360 RPM | 55.3dB(A) | 43.53°C | 0.990 |
| 12.059V | 4.944V | 3.290V | 4.923V | 796.07 | 48.90°C | 115.4V | ||||
| 7 | 63.973A | 7.093A | 7.032A | 2.239A | 839.43 | 89.86% | 2360 RPM | 55.3 dB(A) | 44.46°C | 0.991 |
| 12.042V | 4.932V | 3.283V | 4.910V | 934.12 | 50.60°C | 115.1V | ||||
| 8 | 73.271A | 8.138A | 8.058A | 2.448A | 959.34 | 89.25% | 2360 RPM | 55.3 dB(A) | 45.10°C | 0.992 |
| 12.023V | 4.918V | 3.275V | 4.898V | 1074.84 | 52.80°C | 115.1V | ||||
| 9 | 83.023A | 8.663A | 8.598A | 2.451A | 1079.29 | 88.62% | 2360 RPM | 55.3 dB(A) | 45.59°C | 0.992 |
| 12.005V | 4.908V | 3.268V | 4.890V | 1217.95 | 54.36°C | 115.1V | ||||
| 10 | 92.778A | 9.187A | 9.108A | 2.560A | 1199.23 | 87.91% | 2360 RPM | 55.3 dB(A) | 46.08°C | 0.992 |
| 11.986V | 4.899V | 3.260V | 4.881V | 1364.21 | 56.00°C | 115.1V | ||||
| 11 | 102.927A | 9.206A | 9.135A | 2.563A | 1319.14 | 87.34% | 2360 RPM | 55.3 dB(A) | 44.39°C | 0.994 |
| 11.969V | 4.890V | 3.251V | 4.873V | 1510.35 | 54.98°C | 115.1V | ||||
| CL1 | 0.097A | 14.024A | 14.005A | 0.005A | 117.23 | 79.38% | 2140 RPM | 52.2 dB(A) | 41.34°C | 0.947 |
| 12.135V | 4.951V | 3.327V | 5.023V | 147.68 | 46.91°C | 115.2V | ||||
| CL2 | 99.938A | 1.003A | 1.003A | 1.002A | 1211.11 | 88.32% | 2360 RPM | 55.3 dB(A) | 43.91°C | 0.994 |
| 11.987V | 4.935V | 3.264V | 4.919V | 1371.31 | 52.93°C | 115.1V |
The ST1200-PT's efficiency comes close to the 80 PLUS Platinum spec's requirements in the 20% load test. It's a little further off at 50% load, and under full load it's a full 1.09% away from the 89% mark. Since we run our benchmarks in an environment with a much higher ambient temperature than 80 PLUS, we expect to see lower efficiency. However, this PSU's efficiency just doesn't stack up to the high-end competition in the Platinum category.
SilverStone clearly designed its ST1200-PT for ambient environments cooler than 40°C, and this is shown by its fan profile. As you can see in the table, with even 20% load the PSU's fan goes crazy at warmer temperatures, generating lots of noise. If you plan to push this unit hard somewhere warm, you'll most likely be disappointed by the fan's noise.
Load regulation at +12V is good enough, although competing offerings in this category achieve even better results. The results are satisfactory on the minor rails, as voltage deviations are kept close to 2.5%. That's definitely not ground-breaking performance, but it's not bad, either.
Lastly, we had to conduct our overload (110%) test below 46°C ambient because over-temperature protection kicked in after the full-load test.
