Atrix 500T Extreme 650W Review
paulktreg - June 11, 2008» Discuss this article (8)
Testing (Continued):
AC Ripple On DC Outputs
The noise levels at the AC mains frequency of 50Hz and after rectification at 100Hz, are well within acceptable levels. The maximum noise level occurred at the switching frequency of the power supply, which is approximately 63kHz. (Frequency=1/T. The cycle time of the waveform above is 16uS from peak to peak. Frequency=1/16uS or 1/0.000016 = 62.5kHz). I thought I would include two screen shots of the oscilloscope to show how the noise increased with load. The oscilloscope settings are unchanged and I hope you can see the noise has increased by 100%. (For those of you interested the volts/division is set at 20mV/div and time/division set at 10uS/div).
Noise on the 12V0(1) line with the total power supply load at 107W.
Noise on the 12V0(1) line with the total power supply load at 363W.
This photograph shows 60mV noise on the 3V3 line with the total power supply load at 363W.
This photograph shows 80mV noise on the +5VSB line with the total power supply load at 363W.
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Atrix 500T AC Ripple/Noise Measurements
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DC Output
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+3V3
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+5V0
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+12V0(1)
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+12V0(2)
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-12V0
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+5VSB
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Ripple (mV p-p)
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60
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35
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120
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120
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50
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80
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Pass/Fail
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Fail
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Pass
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Pass
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Pass
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Pass
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Fail
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The Atrix 500T exhibited good AC ripple suppression at 50Hz and 100Hz, but did not perform well at the switching frequency of 63kHz. The ATX12V limits are exceeded on the +3V3 and +5VSB lines and are borderline on the 12V lines.
Temperature, Noise Level And Fan Speeds
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DC Loading
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Temp In (°C)
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Temp Out (°C)
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Δ Temp (°C)
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Fan Speed (RPM)
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107.29W
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20.8
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27.6
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6.8
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998
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262.08W
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19.4
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33.6
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14.2
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1450
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362.77W
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20.1
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44.6
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24.5
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1914
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I am not going to give a pass or fail in this section, as there isn’t really an ATX12V standard to compare against. I will however say the power supply did show signs of stress which I will mention later.
The noise level from the fan was at all times very low. The fan was quiet at the low and medium loads, but did speed up noticeably as the load increased, but this is to be expected.
