Rod Speed wrote:
> q_q_anonymous@yahoo.co.uk wrote
> > Sergio T.P. wrote
>
> >> I've bought a new 400 W power suply. It was supposed to be
> >> a silence power suply. In fact, it is less noisy than my old one,
>
> > actually that is to be expected.
>
> Nope.
>
> > Higher wattage is supposed to be less noisy.
>
> Nope.
>
> > The logic is that it can produce up to 400w because
> > it is more efficient in that it producese less heat, so has
> > less heat to remove. (so the fans needn't spin as fast).
>
> Utterly mangled.
>
> > Maybe if the 400w PSU was also operating at 400w
> > then it could be as loud as a 300w (operating at 300w).
>
> More utter mangling. If both supplys had the same efficiency, the
> 400W supply would have more power lost in the supply itself, so
> with the same fans used, there is more heat to get rid of.
>
> > But I guess typically the 400w PSU won't be using all
> > 400w. Especially not in a computer that ran with a 300w.
>
> Yes, but it wont necessarily be any less efficient than the 300W
> supply, so you should get about the same power lost in the supply.
>
> > If you require 300w , then I guess whether you put a
> > 300w or a 500w or a 700w PSU in there, you'll get 300w.
>
> Yes, you did manage to get that bit right.
>
> > 400w is better though, less strain on the PSU in intensive times.
>
> Utterly mangled all over again.
>

Alright.
I can't find the site that said that higher wattage was less noisy and
other things, but I can believe that it was wrong. Since I haven't read
it elsewhere and it wasn't a famous site or impressive site. And of
course Kony says it's wrong.

> >> but when I turn on the compueter it makes a lot of noise...
> >> It's not a regular noise, like the noise of a fan. It's some kind
> >> of tickling sound... In 3 / 4 minutes it goes lower untill it gets the
> >> normal level of noise of the power supply. Sometimes the noise
> >> disappears when I lift a bit the case and let it down again, or if
> >> I shake a bit the case... Extrange thing is that I had exactly the same
> >> problem with my OLD power supply... (high sound when switching on).
>
> >> It that normal?? perhaps it sounds untill it warm up or something??
>
> > you have to narrow this down. It's important that you
> > sort of found a trigger. THe defeault position causes
> > the noise. But lifting the case a bit stops the noise.
>
> Thats an absolutely classic example of case vibration, that lifting effect.
>
> Presumably the case warms up enough to expand
> whats a bit loose enough so it doesnt vibrate anymore.
>
> It might also be a resonance effect with one of the variable speed
> fans running a little faster once its warmed up so you dont see the
> a resonance effect with the case once its warmed up a bit.
>
> > try taking the power supply out of the case. If it makes a noise
> > then, it's easy to narrow down. If it doesn't make a noise, great.
> > Put it in the case, turn it on, see if there is a noise. If so, take it
> > out, or move it somehow, put it in a bit differently.
>
> Its unlikely to be the power supply given that he
> gets that effect with two different power supplys.
>

yeah, but since this method involves taking the PSU out of the case
anyhow, and running the PSU out of the case, it's part of the process
of trying to put the PSU in without any vibrations. It's also good to
check all possibilities. Especially when it takes 0 seconds longer to
check it.


> > A friend had a similar problem, I think with the power supply.
> > We found that putting some tissue paper between the power
> > supply and the case stopped the noise. Maybe it secured it
> > better and stopped the vibrations.
>
> > Lifting the case is causing some other changes that are stopping the
> > noise. So you have to experiment with moving things, holding things,
> > not holding things, squeezing things. Move PSU from a position where
> > there is noise(screwed in case as it is currently), to a position
> > where there is no noise, finding the dfiferent ways. Move from a
> > position of no noise(e.g. psu out of case), gradually trying to
> > secure the psu, until yju suddenly find noise, then you've foudn a
> > trigger. Hold it in place with your hand in te air. Then against the
> > case. Then with tissue paper between it and the case, with screws in
> > securing the PSU.
>
> > It's possible that there's something knocking the fan inside the PSU.
>
> Nope, you wouldnt get that warmup effect with that and you
> wouldnt get the same effect with two completely different PSUs.
>

That statement you just wrote is only relevant to the last sentence of
mine that you quoted.The rest of what I wrote deals with the vibration
possibility.

And to the possibility you like to attack - of it being the PSU, what I
already wrote in this post applies. i.e. he'll find out if it was the
PSU, in 0 seconds. If it is, then he'll have to cosndier opening up the
PSU.
It that possibility were to take time, or wasn't part of the more
likely, vibration check, then i'd have said "if vibration check
fails... try the following less likely possibility ...."

> > You could open the PSU and move any cable away from the fan.
> > It could be nothing to do with the PSU, it could be that a cable is
> > wacking a case fan.
> > Regarding opening the PSU
> > 2 issues to take into account so as not to hurt yourself
> > * It must be unplugged. Then you won't get electricuted
> > seriously. So that big fear can blow away.
>
> > * That risk above was the big risk. The only risk now is not too bad.
> > It's the charge in the big capacitors, and you touching a big
> > capacitor. They , according to googling, will hurt your finger if you
> > touch them and give you a shock, but probably not much more. You might
> > want to wait for them to discharge. A day maybe to be safe, i'm not an
> > electrician. But if you just open it to check a cable - the fan
> > cable presumably, then you wouldn't be touching them. I think they're
> > covered by a metal thing anyway like a homeless shelter for capacitors.
>
> > And if you're really worried, use your right hand. so electricity travels
> > down your right side, missing your heart which is on the left side.
>
> Makes a lot more sense to not put your hands
> inside the power supply with it plugged in.

I said it must be unplugged - in the first risk - which was the main
risk.

Even when unplugged, you could still have the charge in the capacitors.
(second risk)