Thanks for spending the time to dig that and write all the info, zistu.

I knew about the UPS issue and did test the PSUs connected to both outlet and UPS - same result.

Usually the UPS outputs a squared sine wave only when it runs on battery - it switches to normal sine wave from the outlet when it senses a normal input voltage. I haven't checked mine with a scope to confirm that though.

No problem, was hoping I would have found the cause of your issue, but guess you already ruled out the option of the UPS being the cause.

For your other question, let me express again that I am no expert on this topic. I'm just someone who reads way too much on way too many sites

But from what I understand there are several types of UPSs, ones which do indeed work as you described. But also ones that convert current constantly from AC to DC (charging the battery) and back to AC (draining the battery). That way they can always ensure a controlled output in the event of surges, spikes or complete power failures.

An article by Dan's Data seems to confirm this, at least for the higher end models of UPSs.

One other thing I have wondered about for some time now, but have not been able to find any detailed information on is the following: In some cases buildings or apartment blocks use power converters too to convert a high voltage current to a lower voltage current. As said, I have not found any details on this, but since cost seems to be a factor in all the equipment, I wondered if some constructors of buildings may have shaved off some costs by installing cheaper converters, which do not output the perfect Sine Wave. If that can be true, then you would suffer from the issue regardless if you used a UPS or not.
The only way to conclude that would be to measure, but I lack the equipment, knowledge and problem to test this myself.

I doubt the building converters are an issue. PSUs, like most high power devices, have filters in the input stage to smooth the sine wave that is then used as input signal to the PSU transformer.

The buzz is there at high load or when i scroll web pages with the keyboard/mouse, a clear sign it depends on user activity rather than the noise existent on the 220V line.

I think I'll try my luck with a HX520 from eBuyer. I looked at the very new Seasonic S12II-430 but many people already reported loud buzzes and it's not much cheaper than the HX520 (58 + shipping at scan.co.uk as opposed to 68 + free shipping at ebuyer for the HX520). Plus, the 5 year warranty and modular cables of the HX520 is a nice touch

I'm sorry if that last suggestion sounded paranoid or conspirational. I should have explained my reasoning behind it. I've dug through many forums looking for information on the subject of modern Active PFC PSUs in combination with UPSs and the buzzing noises (which seem to have an origin other than yours, as became clear to me now).
In many of these threads PSUs were send back to the shops where they were tested and found to be in order. The problems described by the owners of these products could not be recreated by those testing the device.
This is what made me wonder about the "raw" form of current provided to the households or offices in which these problems occurred. It may be a weird leap from one point to the other, but it could explain a lot of things.

Additionally, this seems to effect only the latest series of PSUs in the past year or two. I've seen it being reported in certain models of Zalman, Enermax, Corsair, Antec and a bunch of other less known brands. In many cases the UPS was indeed the culprit, but in at least as many other cases the product with the problem was replaced by another brand/model, and working fine. I guess PC's and PSUs have now reached a level of technology where the quality of the input current actually matters and can cause problems if it's not up to spec. If a certain apartment building was being fed "bad" current, then no one would ever notice until they bought a device that had a conflict with it. You won't see a different kind of light coming from your lightbulb if your Sine Wave is perfect or stepped.

I do find it sad that so few support departments of shops and manufacturers are actually aware of the issue, and that no one is taking the effort to warn for these problems. I guess it will have to reach the main stream news first before APC starts putting big "Compatible with Active PFC PSU" banners on their site and product boxes.

I plan to buy a bunch of the Corsairs for some new builds myself soon, and from what I have read they make excellent products. I hope the new unit you'll receive won't have the problems.

I forgot to mention, I tested the S12 at work and at a friend's house in different systems to make sure the culprit was not my system which it powered - same buzz/whine/ticks. I still doubt the noise on the 220V/50Hz line can affect this, or any quality PSU, since it has filters to smooth the sine wave but who knows .

Thanks for the informative posts, I didn't know about the UPS issues.

To be honest I had the hx520 for about 2 months before I started noticing that it was the culprit of the weird electrical noises I was barely hearing out of my p180 at the time. I went to the store and traded it that same day and the new one exhibited the same stuff. You might find it strange because most places have a 30 day return policy. The microcenter by my house is pretty cool about late returns, so thats why that was the case. At the time I didn't really notice it because I had 3 tricool fans set on medium. I wasn't into silence as much as I am now, about 4 months later. I think anyone that says their hx520 is buzz free is probably telling the truth, but I can say for myself that I have extensively tested both hx520s in dead quiet situations. I have doubts that others would go to the lengths that I went to isolate this issue and really listen for it.

I am in the US by the way on 120V. I dont use a UPS.

honestly I am 99% certain you're going to get an annoying buzz if you buy an hx520. If it bothers you, as it did me, I really cant recommend it. The better route would be to buy an older PSU, maybe less efficient, but, silence is the goal here.

of course, I would like nothing more than for you to get this PSU and it be buzz free. I just think these experiences aren't unique, freak occurences. Rather I believe most people either have their fans cranked up too high or just aren't as picky about it. My life experiences show time and time again that I am more picky and sensitive to sound than most people I meet.

Well i hope you're wrong and mine will be whine/buzz free . I also am sensitive about electrical noise. High pitch electrical whine has always bothered me and I can distinguish it regardless of how high other fans are spinning ... the highly different frequency makes it stand out for me.

The HX520 is on it's way and I will let you all know my experience. If it's unbearable then I'm probably gonna give the S12II-430 a try too ...

BTW, reading the Corsair forums, I found one guy experiencing the exact same squealing and chirping sounds that my S12-430 does. He speaks about rthdribl, 3dmark and orthos. He is using the ASUS P5K Deluxe motherboard (I have the P5K vanilla) with a different cpu (i have the E4300).

He attached a recording of the squealing and chirping sounds in the following post too:

http://www.houseofhelp.com/forums/showp ... ostcount=6

It could be a Seasonic "faulty" design, a general issue of recent Active PFC PSUs (see my post above about the switched capacitors) or we have been just plain unlucky ...

Is that sound the same as what you were getting jaldridge6? Anyone else getting these sounds from your PSU? What make and model do you have? 110 or 220V?

Sorry for driving everyone nuts with this

I also went through this high frequency problem like you 1,5-2 years ago. I had an old FSP 350 PNPNF PSU passive PFC, only 1 12V line around 65-72% efficiency and a low power AMD config with Asus K8N. It was a very good PSU but I wanted something more efficient, first I was bought an FSP Green Power it did this high frequency whine. Then I bought a Nexus instead of it which also did the same. I sold this PSU to my friend, he also has a very quiet system (AMD) and there the same PSU doesn't made any high frequency noise. Now I'm using an Intel Core 2 config (Asrock mobo) with Seasonic S12 and I'vent got any high frequency noise. I'm and my friend not using UPS.

So this problem depends on many things, your computer power draw, your mobo-PSU relationship, external influences like UPS and it's hard to avoid this try & buy situation.

Next week my friend will buy a Corsair 520W PSU, I'will listen whether it has any high frequency noise in a Gigabyte mobo + Core2 config.

Its true that under certain loads it'll be loader or quieter. I found that anything under 90W was almost too loud, while loading a single core up to about 115W got rid of a lot of the whine and made the mouse movements not audible.... however, loading up 4 cores and all of a sudden it was like a whining version of my own, personalized hell.

I also have had a S12, the 380 watt version, and it too whined like hell. Should have mentioned that to you before.

Interesting, Tamas, thanks for replying.

I am not doing this because I want to change the PSU. I would use my old Fortron if I could. However, the system refuses to start with the Fortron + P5K motherboard. I also bought a 20 to 24 pin converter, thinking that might be the cause but no luck.

I'm positive the Fortron has enough current on the 5V and 3.3V rails to start it though ... anyone knows a fix to this? Maybe I should have tried harder to fix this instead of going the new-PSU route, but I didn't expect the new PSU to whine. I just bought it thinking I'd shove it in and forget about it.

The HX520 arrived today. Good news and bad news.

Fan is quiet, no complaints there ... if I become a real freak, I can mod it later with an S-Flex.

There is no buzz or chirping sound with the load. There is a very slight buzz if i put my ear right on the PSU vent when running rthdribl or video card stability tester but inaudible at more than 10cm away.

The problem: the freaking unit makes an extremely annoying high-pitch sound that I haven't heard before and it's there all the time, with or without load. It's there with or without video card, hdds, etc. It's there even when I short circuit the power_on atx pins (maybe that's normal since it has no load). I've been running it now for over 2 hours, hoping it goes away but all I feel like doing is shut down the rig asap. It's hard to describe it, it's not a whine ... it is maybe close to the high pitch sound some old TV sets make.

Needless to say, if this doesn't go away, the PSU is going back. I'd rather keep the S12-430 which only whines and buzzes at high load. I'm tempted to try another HX520 as replacement but i feel I'm going that path other took, ending up trying dozens of PSUs; it's like a trap!

Edit: After more than 6 hours, the noise didn't go away. It's there no matter what I do, no matter how I load the PSU. It's going back on monday *sigh*

My friend also bought this PSU, it's running now in a Gigabyte DS3 + Core 2 Duo 2,8GHZ config. I've listened this PSU, a very slight chirping noise can be heard from max. 7-10cm. From half metre it's totally inaudible, this PSU carries less air than S12, so temeperatures've risen in the config after the PSU change.

told ya so

All of them are fucked up. Every last one. I had two. They both buzzed and made weird noises when moving the mouse cursor. The buzz went away under load, but there was still weird shit coming out of it. Try putting your ear up to it and moving the mouse around, loaded, half loaded, and unloaded. I'm sure you'll hear something horrible. Whatever you do, don't buy an earthwatts as a replacement.

You could try the new nexus PSU's. they're not SPCR recommened, but, then again, the hx520, earthwatts, S12, and neoHE --ARE-- and they ALL have fucked up high pitched noises and buzzes. I personally do not trust SPCR even slightly anymore for PSU recommendations. They have lead me astray. You should see what else is out there, take a leap of faith and buy an 80 plus you haven't really heard of. don't get any of the power supplies Ive mentioned.

FSP green or the Nexus nx8060 or something else like that. Tagan makes an 80 plus too. There also that be-quiet thing. I'd like to know more about these models and whether or not they exibit annoying buzz. Also, don't go with the Fortron Zen or the Antec Phantom, I hear they're pretty buzzy too =/

I am going to have to agree that the corsair hx520 does buzz and/or whine. I RMAed mine because it was making a ticking sound, a buzz, and a high pitch electrical noise (similar to the sound when some monitors or TVs are turned off and they start whining). The second one I got 2 days ago has a much quieter whine(one I can deal with), but it still has an electrical operating sound that bugs me.

It is a great power supply, but if you are into quiet, then this supply is not recommended. I would rather have a louder fan then distracting whines, buzz, and noise.

The noise is not LOUD, but it is the most noticeable sound of my rig from about a meter to 2 meters away. It is unacceptable for a psu that is advertised as quiet.

I had a seasonic s12-430 for about 1-2 years. That was really quiet, never new it was on from about 2feet away. Changed because I got new graphics and processor.

I believe these hx520's all make noise. Some people may have a higher ambient noise, more isolating case, or louder fans to hear the noise of this supply.

I may buy a new supply to get rid of the eletrical noise, but I don't know of any recent models that do not have that coil or component noise. I heard that Enermax liberty or infinity maybe a choice for quiet psu's. Any one with Enermax experience?

It might also depend on how old you are - high range hearing naturally drops off as you get older (cf the use of the 'Mosquito' device to deter teenagers from hanging around shops, http://news.bbc.co.uk/1/hi/wales/south_east/4415318.stm).

I find my HX520 to be inaudible (can't hear it above my Noctua fans). I'm in my forties and my high range hearing certainly isn't great so maybe it is whining and I just can't tell!

And just to show how subjective all this is, my previous PSU was a Seasonic S12-430 which I got rid of because it was clearly audible to me.

Phlebas: try sticking your ear up to it. also, i didn't notice it til I swapped out my 1000rpm antec fans [120mm] with 800rpm scythe fans. Well, correction, I noticed some weird noises, but it became obvious to me after the fan swap.

No thanks. I'm not interested in trying to find noise for the sake of it, only what it sounds like in actual use inside a case!

NB: my fans are running at either 5 or 7v. Don't know what rpm that makes them but they are quieter (or at least less noticable) than the Nexus fans they replaced which in turn were a lot quieter than the only Antec fan I tried. If the PSU were making an appreciable sound in the range my ears can hear then it wouldn't be masked out by the fans - which are the only thing I can hear when my system is running.

well, I suppose it is possible that your hearing has worsened over the years. Have you had your ears tested? Its also possible that you just happen to be the only person who may have gotten a decent hx520

I'm about to purchase a new PSU and I was thinking of this one, but now that I'm seeing all these reports of buzzing and whining I don't know. Should I still buy it?

Here's some more data points:
I've built 3 systems in the last few months with HX520 and the PSUs are all very quiet, no whine or buzz at all. I got them from different vendors at different times. They are all in P180Bs with decent fans.
For comparison, the other PSUs I've used recently are the Seasonic 380 and Fortron Green 300. The Seasonic is very impressive, about the same as the Corsair or maybe a little quieter, and the Fortron about the same or a little noisier. The are all way better than the crap I was using before I got the quiet bug and found SPCR

Buzzing indeed seems to be a common problem these days. After an old Antec power supply broke in an even older TBird 1,4GHz machine I replaced it with a S12II-430. Works fine otherwise but it has developed a buzzing sound that intermittently goes away when some activity is going on.

Really annoying considering that Seasonics are supposed to be silent high-quality PSU's. Luckily the computer is about to be phased out (maybe to rare render farm use) as getting a non-buzzing RMA is seems to be unlikely.

If now all Corsairs are buzzing I don't know if I should buy it

Same here. The Enermax power supplies are around the same price.

I want a modular PSU but the M12 is very expensive for a power supply. Does it buzz? What about the modular Enermax model? I don't need anything more than 500 watts.

I have one HX520 and one HX620. No buzzing, no nothing besides of that quiet fan THE best PSU's I ever had.

To people that are claiming no buzz. Have you tried listening to it in a silent room, with only one harddrive and no fans running in the computer? Try loading the CPU as well. I believe that people claiming no buzz haven't actually taken the time, in a silent environment with zero other distractions, to validate that claim. .........It's not an earthshattering buzz, its actually just slightly louder than the fan at its lowest RPM. However, if you have exceptional ears, its easily audible if the rest of the system is dead silent. For me it was such a petty complaint. A tiny little buzz drove me insane with irritation. Most people wouldn't even pay attention to it. I know I didnt even notice it for the first 3 months with the power supply.

I'd almost say that apart of the experience is feeling that the power supply is behaving in a funny way intuitively. Some people have weird connections with their electronics.

Finally, I'd like to point out that I had the power supply for 3 months before I noticed that it was buzzing. I thought maybe it was a time lapsed thing. To test that, I went to the store and bought another one. SUre enough it buzzed out the box.

The fact is you might just not be noticing it. And if you want to stay happy, i'd suggest forgetting about this thread all together

And WHY ON EARTH would I try take out every fan and leave only one disk JUST to be able to hear that "buzz" I do not use my comp in that way. And if you don't have any fans and only using 1 HD why would you need 520W PSU to begin with ? ?? There is NO buzz in my 2 PSUs, my room is silent (very silent) and I use PSU the way there are intended to be used, in a computer system with fans, HDs and stuff. Why ? Becouse ppl buy PSU to run there comps not to listen to it alone...
Try music instead...

Minimum stress on PSU to make it buzz(and it will) sounds like trying to hear noise for just the sake of it. There are better ways to spend time.

I've started to notice the buzz from my S12II-430 which I initially thought was inaudible; there was some, but only at point blank range. I try not to pay attention to it, I've got better things to worry about! ...chief among which a chirp that could be the fan controller display(never before) or a HDD going.

if the buzz is faint one could use a product like this or DIY version to block it.