Noisy Dell PSU?

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Noisy Dell PSU?

Postposted on Mon Feb 16, 2009 7:08 pm

So, I've inherited a Dell XPS Gen 5 that I've made into my primary PC. Only annoying thing seems to be a high-frequency hissing noise that I can't seem to get rid of (it's there whether the case is open/closed, and whether a shake my PC a little bit to try to stop it). This makes me think the PSU is giving off the hiss (since I've also tried to block all the fans systematically, and the noise still persists). Is it common to have this sort of hiss on Dell PSU's. From what I can tell, Dell's PSU's are proprietary, and I can't seem to find a replacement - do they even let you replace/upgrade them? Any advice would be much appreciated.
Dell XPS Gen 5. Intel 955X Express. Pentium D 830 (3.0 Ghz). 4Gb DDR-677 Corsair. Sapphire Radeon HD 4650. Audigy 2zs. Seagate 500Gb, 160Gb. Leadtek WinFast TV200XP Deluxe.
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Re: Noisy Dell PSU?

Postposted on Mon Feb 16, 2009 8:16 pm

Hissing noises are usually due to a phenomenon known as "singing inductors". It can affect any system component that has a switching regulator on it (PSUs, motherboards, video cards). This happens when the windings on one of the inductors (coils) aren't properly immobilized; the fluctuating magnetic field caused by the switching of the regulator causes the windings to vibrate, resulting in squealing or hissing noises.

If it is one of the inductors on the motherboard or video card, you may be able to figure out which one it is by poking at them gently with a non-conductive object. When you touch the inductor that is making the noise, the sound will change. You may be able to quiet it down by putting a couple of drops of thread locker on the coil windings.

If it is one of the inductors inside the PSU, you are best off replacing the PSU. There are potentially hazardous (as in lethal) voltages present inside a PSU even after it has been switched off, so I do not recommend opening it up for DIY troubleshooting. Yes, some Dells had non-standard PSUs; but it is my understanding that most (all?) of them now use standard PSUs.
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Re: Noisy Dell PSU?

Postposted on Mon Feb 16, 2009 9:25 pm

Seems like this one would have to be a non-standard shaped one (circa 2005). The base of the computer takes up the PSU space (very flattened/rectangular... not the traditional "box" shape of most DIY PCs' PSU's).

http://support.dell.com/support/edocs/s ... #wp1057628
Dell XPS Gen 5. Intel 955X Express. Pentium D 830 (3.0 Ghz). 4Gb DDR-677 Corsair. Sapphire Radeon HD 4650. Audigy 2zs. Seagate 500Gb, 160Gb. Leadtek WinFast TV200XP Deluxe.
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Re: Noisy Dell PSU?

Postposted on Mon Feb 16, 2009 9:36 pm

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Re: Noisy Dell PSU?

Postposted on Thu Feb 19, 2009 12:27 am

can't really determine the size. I'm not even really sure how to pull out the PSU - it's like it's the entire base of the case. The sound is really driving me F-ing insane - just high enough a frequency that i can hear it over pretty much everything (TV, fan, heater, airconditioner). Dell charges $90 for a refurbished version of the PSU. I'm not 100% it's the PSU, but i've tried putting a pen on all of the inductors on the board and stopping all the fans one by one - the sound still persists. Is there a way I could unplug the motherboard power and short pins on the PSU to make sure that's it?

EDIT: Just shorted the pins (ie. no mobo plugged in) - and like I've said, I've tried unplugging all the HDs, Cd-drives, and fans... so I guess that leaves the PSU as the only culprit.

It actually looks exactly like that 1U server power supply (except my PSU is 460W)... this model i believe: NPS-460BB-E
I don't understand though, because all the images I'm seeing on the ebay pages for this model, I don't see molex connectors or SATA connectors (for CD drives, harddrives): http://search.ebay.com/search/search.dl ... =NPS-460BB
Dell XPS Gen 5. Intel 955X Express. Pentium D 830 (3.0 Ghz). 4Gb DDR-677 Corsair. Sapphire Radeon HD 4650. Audigy 2zs. Seagate 500Gb, 160Gb. Leadtek WinFast TV200XP Deluxe.
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Re: Noisy Dell PSU?

Postposted on Thu Feb 19, 2009 11:54 pm

Okay, so I need your advice on what this means. I unplugged everything from the PSU, including the two cables that go into the motherboard (the big 24-something main motherboard molecs power cable, and the 8 pin "P2" smaller cable.

When I short the main motherboard cable (to power up the PSU) with the "P2" cable NOT plugged in - no high-pitched noise...
When I short the main motherboard cable (to power up the PSU) with the "P2" cable plugged in - high pitched noise ensues.

Does this imply that the rail that uses the P2 cable on the PSU is what's causing the problem, or that something on the motherboard that's drawing power from the P2 cable is causing the noise (how could this happen if the main motherboard power cable isn't plugged in... and only being shorted, i.e. no main power going through the PSU)?

Thanks for your thoughts. I hope this might imply that what's making the wacky noise is what's on the PSU (although, Dell says my PC's out of warranty and it'll cost $80 to replace the PSU). There are other PSU's with the same basic model number, but most say they're for some other model (not XPS Gen 5), and I don't see enough power connectors (SATA, IDE power, etc.).
Dell XPS Gen 5. Intel 955X Express. Pentium D 830 (3.0 Ghz). 4Gb DDR-677 Corsair. Sapphire Radeon HD 4650. Audigy 2zs. Seagate 500Gb, 160Gb. Leadtek WinFast TV200XP Deluxe.
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Re: Noisy Dell PSU?

Postposted on Fri Feb 20, 2009 10:37 am

Inductor noise often varies with load. So the fact that the noise changes or goes away when you change what's connected is not surprising.

If you really want to rule out the motherboard as a potential culprit, you could try using a spare PSU to power up the motherboard. Since you've got the weird form factor issue, you would need to just set it outside the case, close enough for the wires to reach. And verify that the power connector pinouts are compatible first, just in case Dell has done something really stupid...
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Re: Noisy Dell PSU?

Postposted on Fri Feb 20, 2009 1:57 pm

No dice. Unfortunately, the power layout for this PC is like no other computer's PSU I have (that I could switch out to test).

http://support.dell.com/support/edocs/s ... #wp1052309

12x2 (24) pin main power connector [Labeled (POWER) on the above link], and a
4x2 (8) pin secondary power connector [Labeled (POWER 12V)]

The PSU I have has a 10x2 main power cable, and a 2x2 secondary power connector (not 4x2 like above).

Looking at the Dell link above to the mobo layour, are these power connectors even standard? (I know my PSU is for an AMD board, but are those 24 and 8 pin power cables standard on newer PC's? or are the dell proprietary crap?). I guess I can't be certain that the PSU is making the noise in this case.... maybe unless I also short out that 12V 8 pin connector instead of having it plugged into my motherboard... not sure which to short tho - don't want to electrocute myself).

Any ideas or thoughts (on maybe where I could get a cheap Dell XPS Gen 5 PSU... assuming this is the source of the noise).
Dell XPS Gen 5. Intel 955X Express. Pentium D 830 (3.0 Ghz). 4Gb DDR-677 Corsair. Sapphire Radeon HD 4650. Audigy 2zs. Seagate 500Gb, 160Gb. Leadtek WinFast TV200XP Deluxe.
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Re: Noisy Dell PSU?

Postposted on Fri Feb 20, 2009 4:39 pm

24x2 for the main connector, plus 8x2 for the CPU connector is in fact the new standard for motherboard PSU connectors. Most new PSUs have that connector layout (and also allow you to unsnap the extra 4 pins from both connectors, to allow older motherboards to be powered).

Dell also used to have some motherboards which had a standard physical connector, but with some of the wires scrambled around to make the motherboard incompatible with standard PSUs; using a standard PSU would actually fry the mobo. I'm pretty sure they stopped doing this quite a few years ago, but I would verify that the motherboard expects the voltages on the standard pins before trying another PSU just to be safe.

Edit: Based on the link you posted, the PSU connector pinout does in fact follow the new ATX standard.
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Re: Noisy Dell PSU?

Postposted on Fri Feb 20, 2009 4:51 pm

I just ordered a new psu from this website: http://serverworlds.com/ProductDetail.a ... ctID=25814
This site sells my psu BRAND NEW for $65 (free shipping, no tax), as opposed to Dell trying to charge me $88 + $8 tax + 5 shipping = $101 for a REFURBISHED one. My PSU was about 4 years old, so it's probably a good idea to get a new one regardless (especially if the noise was coming form the psu, as it might be a sign that it's about to kick the bucket). Hopefully it'll solve that high-pitched noise, and if it doesn't... then I guess it's the motherboard (though, I HIGHLY doubt that the case, as I've tested it)... and I should invest in some earplugs.
Dell XPS Gen 5. Intel 955X Express. Pentium D 830 (3.0 Ghz). 4Gb DDR-677 Corsair. Sapphire Radeon HD 4650. Audigy 2zs. Seagate 500Gb, 160Gb. Leadtek WinFast TV200XP Deluxe.
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Re: Noisy Dell PSU?

Postposted on Thu Jan 31, 2013 11:22 am

From the beginning, my Dell Inspiron 620's PSU would be noisy under low power demand conditions. The high frequency rattle instantly went away when a power load was present. With great caution and using an improvised (non-conductive!) stethoscope, I pinpointed the source to the largest transformer located between two large heat sinks. Very inaccessible, and beside, since the culprit was not an inductor, there were really no exposed windings that I could do anything about even if I were able to access the component.

The workstation was still under warranty. I chatted Dell support, saying up front that there was a noisy PSU transformer and that I wanted Dell to replace the PSU. The service rep immediately agreed to a replacement without challenging me or trying to second guess my diagnosis. This was a pretty good outcome for me. Hopefully their response to my request is a sign that some of their staff recognize the problem.

By the way, I don't recommend anyone to poke around the innards of a PSU unless they're well-aware of issues like high voltage arcing distances, and how capacitors can retain a lethal charge even after the PSU has been turned off.
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