Fanless PSU for extreme custom application

PSUs: The source of DC power for all components in the PC & often a big noise source.

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wsc
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Fanless PSU for extreme custom application

Post by wsc » Sat Jun 21, 2003 1:03 pm

Hey everybody, new guy in town. :shock:

I've been busy reading everything I could find on this site about fanless PSU operation. I'm working on a very custom project right now: a small, powerful, portable, nearly silent, and very sexy computer. The whole thing will be milled from aluminum on my friend's new CNC mill :D

What I have been searching for, with really no solid answer to yet, is a powersupply which meets these criteria:

1) Heatsinks are NOT live
2) No hangy bits and bobs (like PFC boards and such)
3) No whines, buzzes, or other noises

The higher quality the PSU is the better. I would much rather try out a high quality 200W unit than a 400W unit of "questionable" quality. In fact, I'm sure 200W will be plenty. However, I'm open to all suggestions as I know some of the best computer items are inexpensive. The powersupply will be "chopped" down to a very slim height as well.

I also have one question relating to fanless operation: After what I've read on this site, I believe that the premature failure of some of the passively cooled PSUs has been due to the lack of airflow over the electrical components like coils, rectifiers, etc, on the PSU board itself. My MOSFETS will be passively cooled on the sides of the case which are essentially HUGE heatsinks. I believe some airflow over the PSU board itself will lead to long term, reliable operation. Can anyone attest to this?

Finally, one question which I may as well ask here is: does it sound feasible to cool both the PSU board and the CPU (Barton 2500+) with one fan using a ducting system? I think it is feasible with the sides of the case aiding in sinking heat from the CPU. Can anyone recommend a fan for this duty? Panaflo is what I'm thinking at the moment.

Anyways - sorry for the long post, thanks for reading. I hope to make some friends here and would love to fabricate a case for anyone who likes the design enough :D

fmah
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Post by fmah » Sat Jun 21, 2003 3:11 pm

Most people like Sparkle/Fortron brand power supplies. Despite the low cost they are well built. Antec is another popular quality brand. Sparkle 300W are only around $35.

There are threads here with passive mods for power supplies. Basically mounting the hot components to an external heatsink.

I would imagine some of the non-sinked parts need some airflow.

MikeC
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Post by MikeC » Sat Jun 21, 2003 4:52 pm

Try a Seasonic: very clean layout, high efficiency, cost not high. If you are going to tear into it, the stamped grill is inconsequential.

Re- airflow or other parts of PSU -- I agree, see Marko's fanless PSU mod. He identifies several very hot components and deals with them by doing "spot HS'ing".

ruprag
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Post by ruprag » Sun Jun 22, 2003 12:46 pm

Some of the fanless systems out there use heatpipe technology to transfer the ehat from the CPU/GPU/NB/.. to the case and then use the case as a radiator.

You can buy some fanless PSU's just see the recomended section.

wsc
Posts: 161
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Location: Oklahoma

Post by wsc » Sun Jun 22, 2003 3:49 pm

ruprag - Those fanless PSUs are far too expensive for my taste (and budget)... I would much rather save a load of money by doing it myself and coming out with a system that works exactly the way I need it to.

MikeC - do you know if the heatsinks are live in the Seasonic PSUs? The EE student inside me believes it might be wiser to start with insulated heatsinks, but I really can't say why, other than my instincts say so.

fmah - I read as much of the fanless PSU stuff as I could find, but I still had a few questions. Oh well.. thanks your help everybody..

MikeC
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Post by MikeC » Sun Jun 22, 2003 3:52 pm

heatsinks live in the Seasonic PSUs? can't recall, sorry...

energy
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Post by energy » Tue Jun 24, 2003 3:23 pm

Only reason heatsinks will or will not be live is the presence of insulating washers between the power transistors & rectifier on the primary heatsink.

These can easily be obtained at electronics shops, but I would still be weary of having a metal case attatched to a live item, even if earthed.

wsc
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Location: Oklahoma

Post by wsc » Tue Jun 24, 2003 8:54 pm

I definitely will be taking every precaution to ensure that the new heat sinks are totally electrically insulated. Only heat will pass through them.

If the original heat sinks are live, steps will be taken to ensure that the PSU operates as normal electrically, but the new sinks will be insulated.

I'm really starting to wonder if I should go with an external PSU.. hmm...

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