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Efficiency, Temperature & Noise


Our efficiency testing procedure is detailed here.

Using results from the previous page, we plotted a chart showing the TPG-1200F1FAP's efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.

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This is a highly efficient PSU under normal loads. However, it doesn't fare so well with light loads.

Efficiency At Low Loads

In the following tests, we measure the TPG-1200F1FAP'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 #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan SpeedPSU NoisePF/AC Volts
11.213A0.493A0.480A0.196A19.66558.180%0 RPM<6.0 dB(A)0.846
22.454A0.980A0.994A0.396A39.77474.531%0 RPM<6.0 dB(A)0.931
33.695A1.477A1.504A5.054A59.89381.363%0 RPM<6.0 dB(A)0.950
44.924A1.975A1.990A0.791A79.82284.846%0 RPM<6.0 dB(A)0.965

We would like to see >60% efficiency during the first test and >80% in the second. Again, under light loads, this PSU doesn't achieve high efficiency. Clearly, its 1200W capacity is a liability in those types of tests. Then again, there are competing PSUs with similar capacities that perform much better under the same load conditions.

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 #5VSBDC/AC (Watts)EfficiencyPF/AC Volts
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CWT has shown that it can design highly efficient 5VSB circuits. But its engineers didn't use one of those in this platform.

Power Consumption In Idle & 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).

Mode12V5V3.3V5VSBWattsPF/AC Volts
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The vampire power we measure is really low!

Fan RPM, Delta Temperature & 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 37°C (98.6°F) to 48°C (118.4°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 37°C (98.6°F) to 48°C (118.4°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 at 30°C (86°F) to 32°C (89.6°F).  

Up to 450W load and with 30-32°C ambient, the PSU operates passively. The fan's minimum speed is quite high though, so from 450W to around 800W, noise output is between 25-30 dB(A). While that's fairly subtle, the transition between passive and active fan mode could be smoother. It takes a load greater than 1kW to make this PSU operate in the 40-45 dB(A) range.

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Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.

  • mapesdhs
    More RGB? *yawn* And is this usefully better in any way in terms of performance, etc. than the old 1275W XT Gold?