Seasonic ST300 making noise when running on UPS

KS400EX · Post by **KS400EX** » Fri Sep 17, 2004 7:21 pm

I have a new Seasonic Super Tornado 300watt psu and a APC LS500 ups and when it switches to battery or is unplugged, the psu makes an odd noise and then changes back to normal when power is restored or ups is plugged back in. Is this normal? It doesn't sound good to me. Has anyone else noticed this with a similar setup or others? I just started using my first ever ups.

acaurora · Post by **acaurora** » Fri Sep 17, 2004 9:02 pm

Does it sound similar to a buzzing noise that is coming through the speakers? Because all the computers I have owned produce that noise whenever the battery backup kicks in.

surfed · Post by **surfed** » Fri Sep 17, 2004 11:13 pm

I believe its because your UPS produces a square wave rather than a sinus wave, thus all your coils (transformers) will humm. Oh, and yes its normal.

Straker · Post by **Straker** » Fri Sep 17, 2004 11:22 pm

this seems reasonably possible - most/many UPSes don't provide AC with a true sine wave form (and it's arguable as to whether that makes a huge diff anyways [edit - as far as the quality of the power, i mean]), although APC is usually pretty zealous about claiming all of theirs do. the frequency/voltage might be changing a bit when the power switches to the UPS too. any of this (simply being "different", not better/worse) could change the noise your PSU makes since most of the noise is usually from the coils, can't think of a halfway decent analogy but it should sort of kind of be like changing the length of a violin string an inch at a time.

i don't know a ton about APFC either, but (this PSU does have that, right?) from what it does, it seems to me that it would make it even easier to make the PSU make funny noises, by changing the waveform of the power the PSU is getting.

KS400EX · Post by **KS400EX** » Wed Sep 22, 2004 5:22 am

Thank you all for you input. I won't worry about it anymore, lol.