Date: Wed, 11 Oct 2006 20:42:14 -0700 From: soralx@cydem.org To: freebsd-hardware@freebsd.org Subject: Re: Quiet computer Message-ID: <200610112042.14698.soralx@cydem.org> In-Reply-To: <3ABF536B-F199-47B9-8B10-EF5A0644BC62@ketralnis.com> References: <3692C07B-CCCC-4756-9B33-6DA724481FF2@ketralnis.com> <200610052145.54292.soralx@cydem.org> <3ABF536B-F199-47B9-8B10-EF5A0644BC62@ketralnis.com>
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> >>> You might wants to consider using a low-power 'brick'-type AC->DC > >>> PSU (~90W?) and a DC-DC voltage converter that plugs directly into > >>> a mainboard's power connector. This will be quite noiseless. > >> Do you have any recommendations? Ideally it would mount on the case > >> (<http://www.logicsupply.com/product_info.php/products_id/134>) like > >> the current power supply does but I'm open to other options > > something like this (random example): > > http://www.logicsupply.com/product_info.php/products_id/596 > > The only types of power supplies with which I'm familiar are the ones > that typically ship with most cases, so I'm a little confused by > this, excuse my obvious ignorance :) > > What does the DC-DC converter do, if the AC-DC converter supplies DC > power? it converts the single supplied DC voltage (that is sometimes allowed to range as much as 6Vdc to 20Vdc) to multiple DC voltages required by the mainboard and other devices (+12V, +5V, +3.3V, -5V, etc) > What would be an example of this AC-DC converter? just any AC->DC power supply that's output is within a DC->DC converter's input range; e.g., a laptop power adapter > Could it power two > 3.5" hard drives in addition to the motherboard? depends on the DC->DC converter you use 3.5" hard drive sucks a lot of juice at 12V line, so the converter must be able to supply that; any converter destined to be used in Intel Pentium4 system _probably_ will work (typical model name for such a beast would look something like '120W', versus '60W' that can supply little power at 12V) note, however, that if you use a good, well filtered AC->DC power supply that produces 12V, you can feed this voltage directly to the hard drives (I think you can; I'm not sure if the groud loop will affect anything) Also, I believe that the more powerful version of DC->DC is more efficient at the same load level than less powerful (i.e., 120W vs 60W) > How does it differ from a regular power supply? much smaller in size, _theoretically_ longer life before {failure because of old age} (assume same temperature), less wires, supposedly more efficient and lower power. The latter, in particular, means that the whole AC->DC->DC system will generate little heat, and thus won't require active cooling (you can even keep the AC->DC PSU outside of case so it doesn't heat up its interior & take up space). Of course, a regular ATX PSU won't dissipate a lot of heat either, yet just disconnecting the fan is hardly a solution. One advantage of such a power source is that realizing uninterruptible power is rather easy: just connect a battery :) This way, you can easily replace a failing AC->DC PSU without sending the server down, too. [SorAlx] ridin' VN1500-B2
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