seperate DC/AC

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

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prochat
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seperate DC/AC

Post by prochat » Fri Oct 08, 2004 1:35 pm

Why is there no products like a PSU that would take 19V DC in entry instead of 110-230 AC ??

All laptops do support this configuration, but no desktop unit !

With such a solution you could install in your home or office a 19V power bus and put the 110-220V AC to 19 DC conversion in a seperate room, all the noise with it !

(or if the product exists, please give me the reference !)

Ph.R.

:?: :idea:

mathias
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Post by mathias » Fri Oct 08, 2004 1:49 pm

The lower the voltage, the higher the amperage needs to be. The higher the amperage, the more the resistance of wires becomes a problem. DC is also more resistance/distance limited than AC.

prochat
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Post by prochat » Fri Oct 08, 2004 2:48 pm

mathias wrote:The lower the voltage, the higher the amperage needs to be. The higher the amperage, the more the resistance of wires becomes a problem. DC is also more resistance/distance limited than AC.
Sure, that means you would need thicker wires. (ex: for 400W, you would need wires supporting 20 A, it's still reasonnable, and 10 meters would be enough to reach the next technical space where noise is not a prob)

Ph.R.

mathias
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Post by mathias » Fri Oct 08, 2004 3:12 pm

prochat wrote: Sure, that means you would need thicker wires. (ex: for 400W, you would need wires supporting 20 A, it's still reasonnable, and 10 meters would be enough to reach the next technical space where noise is not a prob)
But most people don't have another room to put a noisy power supply in. Plus it's just plain over the top. And if you could easily have a 19V extarnal power supply, you might as well go all the way and just have it produce 12v power.

Semi-external power supplies have been discused here before. The important thing is not to have the bulk of the PSU far away from you, but to have it outside the PC, ie. not above the CPU, not insulated by the case, and not confined to the limited PSU space. My understanding of this is, the external portion would provide something like 48V to be converted into 12V, and 40V to be converted into 5v and 3.3v.

I think a semi external power supply would be great not only because of noise reduction, but also because, if they were easily detachable, they could reduce the weight of the PC(and my PC is getting quite heavy). They should be designed to maximize this.

Edit: Although a two piece PSU could quite easily be fanless, I don't think that should be the only kind. I think the portion inside should help out with the airflow, with a manualy adjusted fan, or even one that you'd choose and attach by yourself to the outside. It could either be a 12cm fan at the bottom, or a regularly positioned 8cm fan so that the (inner portion of the)PSU could be smaller than a normal one and leave a little extra room for a CPU heatsink. The external portion could instead of being fanless have a very low speed fan and be designed as a windtunnel; to reduce the cost.

With a such two piece units, the two parts should be sold seperately, to seperately choose either the fanless internal part, or the airflow assisting version, and the fanless external part, or the cheaper windtunnel one.

ascii
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Post by ascii » Fri Oct 08, 2004 5:24 pm

The rumoured Zalman fanless PSU that has been discussed on this forum seems to be pretty close to what mathias is suggesting, except for the fan part. Not sure why you would want to couple a fan with the internal half of a PSU with a fan. You can just buy an additional low noise fan if it's getting to hot in the computer. Doesn't make sense (to me) to bundle it with the PSU it the PSU doesn't need it.

hvengel
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Post by hvengel » Sat Oct 09, 2004 10:16 am

Fanless high amperage single voltage DC power supplies are available with more than enough power to handle a PC. These units have been in production for decades and are large and some what costly. The limitation is that the DC to DC converters (to convert 12V DC into 5V and 3.3V DC) that are available have limited capacity and are only enough for modestly powered PCs.

mathias
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Post by mathias » Sat Oct 09, 2004 10:59 am

ascii wrote:The rumoured Zalman fanless PSU that has been discussed on this forum seems to be pretty close to what mathias is suggesting, except for the fan part. Not sure why you would want to couple a fan with the internal half of a PSU with a fan. You can just buy an additional low noise fan if it's getting to hot in the computer. Doesn't make sense (to me) to bundle it with the PSU it the PSU doesn't need it.
Except it doesn't look all that easily detachable (probably an improvment over regular PSU's, but not enough). Plus it's apparently all external(which probably is a better idea).

I'd actually only be interseted in the a wintunnel one, I doubt I'm alone, the market would probably be much bigger for cheap very quiet external PSU's, and also reasonably priced quiet ultra high powered windtunnel PSU's.

The zalman unit will probably be easily modable for quick detachability, but it seems like it'll be very expensive.

prochat
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Seperate

Post by prochat » Mon Oct 11, 2004 1:13 pm

I totally agree with the argumentation of mathias, and still wonder why no one does provide this (or does only for laptops) ?


BTW: which Zalman model is fanless and can be installed outside the box ?

Ph.R.

icancam
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Post by icancam » Sun Oct 17, 2004 1:47 pm


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