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Efficiency, Temperature & Noise
Efficiency
Our efficiency testing procedure is detailed here.
Using results from the previous page, we plotted a chart showing the 450 BT’s efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.
The majority of PSUs with a similar capacity and 80 PLUS rating achieved higher efficiency under normal loads. But under light loads, the 450 BT took the lead from Corsair's CX and CXM models.
Efficiency At Low Loads
In the following tests, we measured the PSU'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 | 1.212A | 0.486A | 0.477A | 0.194A | 19.448 | 68.090% | 890 RPM | 20.1 dB(A) | 0.505 |
| 11.853V | 5.123V | 3.339V | 5.152V | 28.562 | 115.34V | ||||
| 2 | 2.490A | 0.978A | 0.987A | 0.389A | 39.879 | 77.464% | 1034 RPM | 25.3 dB(A) | 0.653 |
| 11.883V | 5.107V | 3.338V | 5.145V | 51.481 | 115.32V | ||||
| 3 | 3.695A | 1.470A | 1.467A | 5.138A | 59.347 | 81.125% | 1120 RPM | 27.6 dB(A) | 0.742 |
| 11.896V | 5.099V | 3.337V | 5.138V | 73.155 | 115.30V | ||||
| 4 | 4.974A | 1.963A | 1.975A | 0.780A | 79.803 | 82.994% | 1186 RPM | 30.0 dB(A) | 0.796 |
| 11.904V | 5.094V | 3.337V | 5.131V | 96.155 | 115.27V |
Under light loads, the 450 BT achieved satisfactory efficiency levels given its low price. The PSU's fan spun at high speeds though, mostly because the operating temperatures during those tests were above 30°C.
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 | 75.328% | 0.038 |
| 5.151V | 0.685 | 115.38V | ||
| 2 | 0.250A | 1.287 | 78.571% | 0.090 |
| 5.147V | 1.638 | 115.38V | ||
| 3 | 0.550A | 2.827 | 79.589% | 0.181 |
| 5.138V | 3.552 | 115.37V | ||
| 4 | 1.000A | 5.125 | 79.680% | 0.282 |
| 5.123V | 6.432 | 115.37V | ||
| 5 | 1.500A | 7.662 | 78.860% | 0.356 |
| 5.107V | 9.716 | 115.38V | ||
| 6 | 2.501A | 12.685 | 74.993% | 0.438 |
| 5.072V | 16.915 | 115.36V |
The 5VSB rail achieved high efficiency levels. We've seen much more expensive power supplies fare worse in these tests.
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 | 11.900V | 5.104V | 3.379V | 5.157V | 4.786 | 0.411 |
| 115.3V | ||||||
| Standby | 0.045 | 0.003 | ||||
| 115.3V |
Vampire power remained low in both test cases.
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 30°C (86°F) to 40°C (104°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 30°C (86°F) to 40°C (104°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).
Even with minimal load, the fan generated more than 30 dB(A). Its profile could be less aggressive under light and moderate loads, but apparently RSY wanted to stay on the safe side.
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