Hi all,

I would like to replace my PSU's stock fan with a slower one. The stock fan is a 34 CFM, and i'm thinking of a 26.5 CFM Papst 8412 NGML or 19.4 CFM Papst NGL as a replacement.

I guess the odds of frying my PSU are very low, but I'm concerned about what exactly would happen if the PSU fails on me. Would it produce smoke, burn, explode ? Or would it simply shut itself down ? I know this may sound like a weird question, but my computer being on 24/7, and my girlfriend and I sleeping next to it, I really need to know if I am taking a risk or not.

Thanks !

If you're worried or at all in doubt, buy a new power supply that's rated as being silent by the folks around here. Many other places think something's silent if they can't hear it well over 3 3500 rpm case fans, the Vantec Tornado on their CPU, a Geforce FX 5800 Ultra, and their 15k rpm SCSI drives...

Seriously though, if you're worried about it now, it'll probably always be in the back of your mind, unless you can state which exact power supply you have and can find out from some place like Tom's Hardware what their copy of your particular model actually did when they tested it until meltdown. Some PSUs die a nasty death, while others actually have _working_ thermal overload protection in them.

The Sparkle/Fortron/Aopen/Power Man 60PN series is supposed to be almost completely silent and have a really good rep for delivering power. The best part is that the 350w model is $45-$48 US, and the 300w is even cheaper and available for less than the 350 at newegg.com. If you're on a budget, sell your old one to recoup probably half of what the new one would cost you.

How dangerous it is depends on

1) quality of PSU and its components
2) actual load / heat in PSU

I recently heard some stories about unmodded, stock, low-quality PSUs literally bursting into flames while in operation (Ever heard of a car called the Chevrolet Corvair? In the 1970s Ralph Nader wrote a book about it called Unsafe at Any Speed.)

For your 24/7, I'd err on the side of caution. Unless it is an expensive high quality PSU, why not just replace it with a quiet one? There are lots.

Thanks for your comments guys. My PSU is the stock PSU brought with the Aopen HQ45 case, and seems to be a Fortron. Following Kawboy's advice, I had a look at tom's hardware but couldn't find a review for it.

However, I found this : http://www.tomshardware.com/column/20011012/index.html

This tends to prove MikeC right : even an unmodded PSU can turn into a ball of flames, and I *really* don't want such a thing to happen while we are sleeping in the same room. I'll stick with the stock PSU, which is not that noisy, and buy a brand new (silent) one when it becomes the most noisy component in my computer (I still have to replace this whining IBM 40Gb drive with a Seagate).

I've heard that if you have a fire and the insurance company finds you opened/modified something like a power supply then they may not provide any coverage.

Aside from that I think I may make a new box fitting a PS but with a 120mm fan opening blowing straight thru.

My recently modded Enermax 365-whatever just became unstable. It rebooted the computer randomly and often. I turned up the rheostat, but it was too late. The crashes became less frequent, but almost anything worth doing on a computer would still trigger reboot. My 5 volt line dropped into the low 4's according to the VIA HW Monitor.

My mod was fairly conservative. For the bottom 92mm fan I put in a 7-volted Panaflo (M-speed I think) and the 80mm rear exhaust was changed to an L-speed rheostated down to barely audible. I did NOT block the front vents: my case has significant airflow (kinda went crazy with multiple rheostatted-down 120mm Panaflo-L's a year ago), so forward exhaust is not a problem.

How do I know it was the PSU? Substituting in my old (noisy) Sparkle 300W fixed everything... except the $1000 I've just spent on a replacement system. Guess my 4 year old finally gets a computer! The good part is, I get to mod a Lite On FS020!

From your description, it does not sound like overheating was an issue. Enermaxes have a pretty high failure rate; maybe this one was going to go, one way or another. Same with the first one I had. (yeah, means I got a second one, which also died Sometimes learning is only achieved by repetition. )

Modding your PSU isn't remotely dangerous....unless you get electrocuted. Then it's very dangerous.

Just unplug your comp and press the power button a couple of times. If you are really unsure stick some kind of metal from the ground of the psu to the ground of the wall jack.

Also waiting a day or so with it off the wall will work. I went for it on my and touched everthing that would shock me and I got nothing.

Maybe it is because I work as an electrician and have been shocked enough not to be scared or maybe it is just because I am not too bright.

I'm quite certain I've heard somewhere that the capacitors in a PSU will carry enough charge to give you a good zap even if it is unplugged. Can any confirm/deny this?

Yes, the capacitors will carry a charge for some time. Letting the PSU sit unplugged for a few hours should give it enough time for the charge to bleed off.

As long as you are careful just go for it. The risk really isn't that high most people are just a lot more scared of electricity than they need to be.

To be really confident go to your comp hardware store and by a wrist grounding strap. Plug it in to the ground in you wall and you should have no worries. It is also nice to have just for working on your comp normally because it grounds you so there is no risk to static shocks on your hardware.

But just to say how much it matters they cost $6 and I have never bothered to pick one up.

Grounding straps have a built in resistor to prevent you from shock. The idea is that all of the electricty goes out through this ground instead of through your body.

The static electricity I was talking about was just for general computer hardware. If you are working inside the case and have some built up static in you it can take out a board pretty easily.

I haven't bothered to get one either and guess what? I zapped myself inside my power supply the other day, too! I had it connected to the board but outside the case with the cover off experimenting with different places to stick the thermistor. I started out with the thing unplugged, but after a few tries I forgot to unplug it and apparently got zapped by brushing my hand against one of the heatsinks. Not positive, though, because I wasn't watching my left hand and very rapidly removed it!

To get on topic, though, I didn't notice a difference in fan RPM from placing the thermistor outside the PSU but inside the closed case to inside the PSU right next to the center of the exhaust fan. Bloody stock fan winds up to 3700 rpm under load!!! 3375rpm at idle now while surfing the web. Ugh. Guess I'll try to find the 12v supply in there and just put a stock speed Panaflo L. The ones I have aren't exactly silent, though. They're got a tick in them at 12v.

Yes, that was the plan. Man, did I ever learn a lesson about who to listen to when reading that a PSU (or whatever) is silent. Always always always find out what other components are in the system! Overclockers are bad judges of silence because most of them have several noisy fans in their systems that drown out a moderately noisy sound source like the Enermax.

Oh well, I still have my feelers out for one of the Forton 60PN PSUs. I can get one of the 350w ones from xpdirect.com, but they won't take a Canadian Visa and I have to prepay via money order. Also, shipping works out to a rather unreasonable $30 Canadian on top of the PSU price.

I'm currently looking for a Canadian source for the Aopen-branded part. Aopen dealers are a dime a dozen, so as soon as they're available I can get one locally.

I charged up a 6800uF capacitor to about 18V maybe over a month ago, and it still measures over 14V. But PSUs have bleeder resistors across the big capacitors that should discharge them completely in twenty minutes.

The ATX spec states that all failures must be self contained, take a look at

http://www.rotting-energy.net/PCR/test/ ... v_spec.pdf

Page 10, 3.1.5 .

Of course, no one can really predict what will happen if something blows, but either way, is not *supposed* to go bang, throw flames, excessive smoke etc.

yes, but at Tom's they were making the PSU's do things you will never make them do. Your 300watt PSU is never going to get much past 200watt draw, if even that much.