External or fanless PSU for PC - any better?

Hey everyone,

Though I hope to one day afford a fully 12V DC computer, that isn't happening yet, so I still use this regular PC. A while ago the power supply died,and I replaced it with a cheap-o fifty dollar generic one. It is loud!, especially when the computer warms up. Not only is there typical mid-high frequency fan noise, but it can also turn into this low pitched rumble whichI find very aggravating/disturbing, you know, a low frequency motor rumble(made even worse, I think, from sitting in the compartment of this computer desk, whihc may act as a resonant cavity for the sound).

I've been looking at either external power supply units, or fanless PSUs. I like the thought of an external PSU because you can move it far away from you, outside of the computer - I'm guessing as far away as you want, withlong enough cables? Or am I mistaken on this point. However, I think the external PSUs still use fans.

On the other side of things are the fanless PSUs which have fins or perforations all over them to act as heat sinks/releasers and dissipate high temperature inside the computer case. I like the sound of them because, well, there is no sound from them! Concentrating on work on the computer would probably be easier for me without the noise (I know for certain it would be easier without the rumble of the current PSU I have!)

Too bad that either of the PSU types (external with a fan or internal and silent with no fan) are still switching power supplies, which I've since been taught aren't so good because they can emit frequencies from the switching of AC to DC (if that's correct?). Would a fanless power supply, even if it's a switching power supply, be any better, EMF-wise, than a regular PSU since it's not using a motor to run a fan?  

Also, I saw at least one which claims to have a "Built in EMI filter, low ripple noise" - a built in electromagnetic interference filter, eh? That *sounds* interesting. Could this be of benefit by preventing RF-dirt from passing onto cables? I'm not sure what they mean by "low ripple noise", thoughI presume it has something to do with the EMI filter.

Forgive me if this has been discussed, but is there a difference from one switching power supply to the next, in regards to the unwanted frequencies they produce? And can the frequencies be blocked, somehow?

Are there any questions I could ask manufacturers to determine anything about the type of frequency to determine ahead of time what it is, how strong it is, or if it's there at all?

Thank you for your help. I know it's just a temporary solution, but if I need to use this PC more before I can afford something else, making it as pleasant as I can isn't a bad idea.  

Cheers,

R.ticle One

> Also, I saw at least one which claims to have a "Built in EMI filter, low
> ripple noise" - a built in electromagnetic interference filter, eh? That
> *sounds* interesting. Could this be of benefit by preventing RF-dirt
> from passing onto cables?

In theory this would be a good thing, however, I recently purchased a
custom-built computer that was supposed to have a high quality, low
noise power supply, and I found the computer really nasty
to be around (although *why* this was I was never certain, and I quickly
returned it -- for all I know, it could have been an offgassing
problem).

I did notice that the Lenovo Thinkcentre desktop PC with the "Ultra
Small Form Factor" has an external power supply, which I thought was
interesting, because like you said, you can put it even further away
from you than your computer. Although I'm not personally convinced
that the PC power supply is the cause of my problems...

Marc

In a message dated 3/9/2009 10:55:33 P.M. GMT Standard Time,
[hidden email] writes:

interesting, because like you said, you can put it even further away
from you than your computer. Although I'm not personally convinced
that the PC power supply is the cause of my problems...




most likely all the open circuitry evan if you faraday this then you have
the problem of the keyboard and mouse, the new solid state computers are worth
a look, they will get bigger, how about one of these and a pico prjector all
off battery ?


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