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.
Efficiency, Temperature & Noise
Efficiency
Our efficiency testing procedure is detailed here.
Using results from the previous page, we plotted a chart showing the Caslon II’s efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.
Overall efficiency under normal loads is low, while the situation gets better with light loads.
Efficiency At Low Loads
In the following tests, we measure the Caslon II's efficiency at loads significantly lower than 10 percent of its maximum capacity (the lowest load the 80 PLUS standard measures). The loads we dialed were 20, 40, 60, and 80W. This is important for representing when a PC is idle, with power-saving features turned on.
| Test # | 12V | 5V | 3.3V | 5VSB | DC/AC (Watts) | Efficiency | Fan Speed | PSU Noise | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.178A | 0.482A | 0.470A | 0.194A | 19.298 | 68.121% | 910 RPM | 25.8 dB(A) | 0.788 |
| 12.071V | 5.170V | 3.378V | 5.147V | 28.329 | 115.24V | ||||
| 2 | 2.441A | 0.967A | 0.974A | 0.390A | 39.724 | 76.809% | 921 RPM | 25.9 dB(A) | 0.923 |
| 12.064V | 5.158V | 3.376V | 5.130V | 51.718 | 115.21V | ||||
| 3 | 3.636A | 1.454A | 1.451A | 5.115A | 59.243 | 80.680% | 930 RPM | 26.1 dB(A) | 0.974 |
| 12.063V | 5.147V | 3.374V | 5.115V | 73.430 | 115.18V | ||||
| 4 | 4.897A | 1.945A | 1.955A | 0.784A | 79.674 | 82.709% | 1006 RPM | 28.5 dB(A) | 0.961 |
| 12.066V | 5.139V | 3.372V | 5.101V | 96.330 | 115.15V |
With light loads, the Caslon II achieves decent performance given its low efficiency certifications.
5VSB Efficiency
The ATX specification, along with CEC, ErP Lot 3 2014 and ErP Lot 6 2010/2013, states that 5VSB standby supply efficiency should be as high as possible, recommending 75 percent or higher with 550mA, 1A, and 1.5A of load. The PSU should also achieve higher than 75% efficiency at 5VSB under full load, or with 3A if its max current output on this rail is higher than 3A.
We take six measurements: one each at 100, 250, 550, 1000, and 1500mA, and one with the full load the 5VSB rail can handle.
| Test # | 5VSB | DC/AC (Watts) | Efficiency | PF/AC Volts |
|---|---|---|---|---|
| 1 | 0.100A | 0.516 | 66.409% | 0.115 |
| 5.156V | 0.777 | 115.36V | ||
| 2 | 0.250A | 1.287 | 75.484% | 0.212 |
| 5.147V | 1.705 | 115.37V | ||
| 3 | 0.550A | 2.821 | 79.398% | 0.307 |
| 5.128V | 3.553 | 115.35V | ||
| 4 | 1.000A | 5.103 | 78.375% | 0.365 |
| 5.103V | 6.511 | 115.36V | ||
| 5 | 1.500A | 7.609 | 78.638% | 0.395 |
| 5.072V | 9.676 | 115.35V | ||
| 6 | 2.500A | 12.508 | 77.096% | 0.429 |
| 5.003V | 16.224 | 115.34V |
The 5VSB rail is not particularly efficient, matching this PSU's general overall performance.
Power Consumption In Idle And Standby
In the table below, you'll find the power consumption and voltage values of all rails (except -12V) when the PSU is idle (powered on, but without any load on its rails), and the power consumption when the PSU is in standby mode (without any load, at 5VSB).
| Mode | 12V | 5V | 3.3V | 5VSB | Watts | PF/AC Volts |
|---|---|---|---|---|---|---|
| Idle | 12.036V | 5.202V | 3.379V | 5.161V | 10.266 | 0.298 |
| 115.4V | ||||||
| Standby | 0.160 | 0.025 | ||||
| 115.4V |
With the zero-wattage mode deactivated, this PSU consumes 0.16W in standby with 115V input, and a bit more with 230V input. Most of the PSUs we test stay below 0.1W with 115V.
Fan RPM, Delta Temperature, And Output Noise
Our mixed noise testing is described in detail here.
The first chart below illustrates the cooling fan's speed (in RPM), and the delta between input and output temperature. The results were obtained at 36°C (96.8°F) to 47°C (116.6°F) ambient temperature.
The next chart shows the cooling fan's speed (again, in RPM) and output noise. We measured acoustics from one meter away, inside a hemi-anechoic chamber. Background noise inside the chamber was below 6 dB(A) during testing (it's actually much lower, but our sound meter’s microphone hits its floor), and the results were obtained with the PSU operating at 36°C (96.8°F) to 47°C (116.6°F) ambient temperature.
The following graph illustrates the fan's output noise over the PSU's operating range. The same conditions of the above graph apply to our measurements, though the ambient temperature was between 30°C (86°F) to 32°C (89.6°F).
The fan profile is not loose, which we expected since this platform offers low efficiency levels. With up to around 275W, the PSU is in the 30-35 dB(A) range, while higher loads push it closer to 40 dB(A). If you need a quiet PSU, then shop for a more efficient one.
MORE: Best Power Supplies
MORE: How We Test Power Supplies
MORE: All Power Supply Content
Alarming amount of Texas Instrument chips found in Russian-based weapons in Ukraine — Russian military using third parties to purchase U.S-made chips
Aoostar AG02 eGPU dock with OCuLink support and 500W PSU announced for $219
China levels anti-trust charges against Nvidia – country accuses chipmaker of violating anti-monopoly regulations, examining the $7 billion Mellanox acquisition
