What exactly is a 'quiet' PSU?

Originally posted by Vehementi
I think it depends on the brand. Good, quality brands like Enermax, Antec, etc. silence their PSU's as much as they can. But other, cheaper brands just put lower-RPM fans on to denote "silent".

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I found my AOpen case to be a good all rounder with plenty of room for expansion and I assumed that because the PSU was also the AOpen brand it would make some difference to noise.

Its no quieter than my previous case. I may consider a new PSU eventually as if they run at 25-30dB as advertised, they will be very quiet indeed.

PS. for the record, the electrical noise I speak of from a PSU can be more commonly known as the "audible coil buzzing" component inside of it.

I assume the noise you refer to is the same a TV or computer monitor also can emit, it's extremley high pitched, for example my father can't even hear it but it drives me crazy...

My new TV has that problem when it starts but after just a few seconds it disappears, I guess it changes some frequency to get rid of the noise somehow...

A friend to me however has an older TV and that one starts to emit the noise after a while, presumable when it has gotten warm, and it doesn't stop if you don't turn of the monitor and let it cool of...

I have just the exact same problem with an old 14" computer monitor, but I found out that if I change the frequency with powerstrip down or up a few hertz the noise stops...

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But back to your Q, what the PSU manufacturers refer to is that the fan is thermalcontrolled, i.e. if the PSU is cool the FAN will slow down and counterwise when it gets hot...

I have a 431w Enermax PSU myself and it's one extremley quiet PSU I must say, highly recommended!

On a side note I've never heard a PSU emit this "electrical noise" (which I also explained above...)

PSU "electrical noise" = the high pitch whine emitting from it as well as the PSU's own fan noise.

Your PSU emits a high-pitced whine? I haven't heard any from my 400w.

Originally posted by Vehementi
Your PSU emits a high-pitced whine? I haven't heard any from my 400w.

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Thats because u have an Enermax Whisper.

Apparently, Scan have very cheap own-brand PSUs which all claim to use "Active PFC", "Dual Fans" and "Super low noise" from £30 upwards. I'll have to find out more about these.

My theory is that you only hear this coil sound from (low-quality) PSUs when they're under heavy load. I have two PSUs in my computer right now and the other, older one, makes some noises every now and then. Not loud but it's audible because the system itself is quiet.

Another interesting thing are these New PSUs from Hiper PC Ltd.

The only review here claims they are "Enermax beaters" and i have seen them @ eBuyer for "at least 25% cheaper than Enermax".

I suggest replacing the fan in the PSU with an 80mm from Panaflo or Papst; this is the cheapest, most effective way to quiet the PSU fan noise. I did this on my Antec PSU with Thermally Controlled fan, it's now whisper quiet. The Papst is worth the slightly higher expense than the Panaflo, IMO. In addition, a wire fan grill will be quieter than a grill made of flat, pressed metal. Most cheap PSUs have a grill pressed out of the PSU casing...cut it out and replace it with a wire grill when you replace the fan.

The loudest thing in my system now is the HD! I reduced the sound of the HD around 50% by relocating it but it's still a bit loud. Good Luck!

Originally posted by Elcarion
The Papst is worth the slightly higher expense than the Panaflo, IMO.

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IMO as well. Papst fans are excellent because they balance them perfectly, eliminating any vibration at all.

From the Anandtech Socket A Cooler Roundup
The Papst fan we received for testing was a 8412NGL unit, which is the quietest Papst 80mm fan.Thanks to its Sintec PTFE sleeve bearing, it is extremely quiet. Another "speciality" of Papst fans is that, in order to prevent vibrations, they are exactly balanced, thanks to tiny metal weights sticked into little slots around the fan motor - as you can see on the picture on the right, the weights are marked with red circles.

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Hey, Snowy

I think i got the same prob with ya, got this cheap 300w PSU last Christmas...It's a bit noisy with some screeching noises from the fan during booting.

Here's a related article from Tom's Hardware. It's a good read if you get a chance: http://www.tomshardware.com/howto/02q4/021021/index.html

Originally posted by Snowy Commando
My current Aopen 300W PSU is fine apart from the medium-pitch electrical whining noise that the PSU makes like i've heard before with all other PSU's that come supplied with a case.

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Electrical whining noise is caused by cheap components, I know from experience of buying cheap cases with cheap PSUs. Does yours whine even when the Power Switch is turned off (i.e. still plugged in to socket, turned on, but ATX switch not pressed), drove one of my customers mental till I bought him a more expensive PSU.