From owner-freebsd-hardware@FreeBSD.ORG Thu Oct 12 03:42:23 2006 Return-Path: X-Original-To: freebsd-hardware@freebsd.org Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 13AD316A412 for ; Thu, 12 Oct 2006 03:42:23 +0000 (UTC) (envelope-from soralx@cydem.org) Received: from pd2mo3so.prod.shaw.ca (shawidc-mo1.cg.shawcable.net [24.71.223.10]) by mx1.FreeBSD.org (Postfix) with ESMTP id 8A39443D53 for ; Thu, 12 Oct 2006 03:42:19 +0000 (GMT) (envelope-from soralx@cydem.org) Received: from pd2mr7so.prod.shaw.ca (pd2mr7so-qfe3.prod.shaw.ca [10.0.141.10]) by l-daemon (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0J700026G7MKSD90@l-daemon> for freebsd-hardware@freebsd.org; Wed, 11 Oct 2006 21:42:20 -0600 (MDT) Received: from pn2ml9so.prod.shaw.ca ([10.0.121.7]) by pd2mr7so.prod.shaw.ca (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0J7000GIP7MJYVO0@pd2mr7so.prod.shaw.ca> for freebsd-hardware@freebsd.org; Wed, 11 Oct 2006 21:42:20 -0600 (MDT) Received: from soralx.cydem.org ([24.87.27.3]) by l-daemon (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0J7000I0W7MJD680@l-daemon> for freebsd-hardware@freebsd.org; Wed, 11 Oct 2006 21:42:19 -0600 (MDT) Date: Wed, 11 Oct 2006 20:42:14 -0700 From: soralx@cydem.org In-reply-to: <3ABF536B-F199-47B9-8B10-EF5A0644BC62@ketralnis.com> To: freebsd-hardware@freebsd.org Message-id: <200610112042.14698.soralx@cydem.org> MIME-version: 1.0 Content-type: text/plain; charset=iso-8859-1 Content-transfer-encoding: 7bit Content-disposition: inline References: <3692C07B-CCCC-4756-9B33-6DA724481FF2@ketralnis.com> <200610052145.54292.soralx@cydem.org> <3ABF536B-F199-47B9-8B10-EF5A0644BC62@ketralnis.com> User-Agent: KMail/1.9.1 Subject: Re: Quiet computer X-BeenThere: freebsd-hardware@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 Oct 2006 03:42:23 -0000 > >>> 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 > >> () 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