XFX 550w Pro buzzing on UPS.

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rvg90

rvg90

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Jan 14, 2012
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Hello, i have a 900w Legrande UPS that i mainly bought to watch WC games with all the power outages here and usually it kept my TV up for 1-1.5 hours but now as i dont need it on my TV i decided to switch it on PC to gt ive me few minutes to shut it down however as soon as i plugged it in the power supply and the monitor started buzzing so i decided to avoid turning them on and immediately unplugged them. The UPS itself buzzs loudly but i was told that its normal for anything that generates powe but is it normal for plugged in equipment to buzz louder than normal?
 
Solution
ko888
There is a known compatibility problem with power supplies based on Seasonic's S12-II 520 Bronze model (i.e. the XFX 550W Pro is based on a modified Seasonic S12-II 520 Bronze to output 30 watts more power) when using a non-sinewave UPS. The incompatibility will show up as an overload condition on the UPS even though the UPS may have more than enough capacity.

The Legrand UPS Niky 1000's output waveform is Pseudo-Sinusoidal.

You would need to use the Legrand UPS NIKY S 1000 model that has a perfectly sinusoidal output waveform.
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ko888

ko888

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Feb 18, 2009
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APFC power supply units, like the XFX 550W that you have, may buzz with a UPS that outputs a simulated sinewave (i.e. stepped approximation to a sinewave, square wave, triangle wave). It's caused by the interaction between PSU's APFC circuit and the UPS' output wave form.

Pure sinewave UPS don't exhibit that problem.
 
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rvg90

rvg90

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I tried to put the PC on it and the second the power turned off it generated a long solid beep then turned off, i was able to turn it back on after unplugging my PC from the socket. According to the user manual a long beep indicates overload\failure but i don't understand the problem here it should be 900w and my power supply is 550w + 40w monitor(LED) + creative speakers which i am sure wont take more than 100w and the router. My PC wasn't at full load as well.

That is my exact model

http://ups.legrand.com/wp-content/uploads/2011/07/UPS-LGR-0056-GB.pdf

EDIT: Actually it's 600w not 900 maybe i surpassed that and that's why it failed...
 
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ko888

ko888

Titan
Feb 18, 2009
16,708
41
84,990
There is a known compatibility problem with power supplies based on Seasonic's S12-II 520 Bronze model (i.e. the XFX 550W Pro is based on a modified Seasonic S12-II 520 Bronze to output 30 watts more power) when using a non-sinewave UPS. The incompatibility will show up as an overload condition on the UPS even though the UPS may have more than enough capacity.

The Legrand UPS Niky 1000's output waveform is Pseudo-Sinusoidal.

You would need to use the Legrand UPS NIKY S 1000 model that has a perfectly sinusoidal output waveform.
 
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