Date: Wed, 22 Aug 2001 12:09:08 +0200 From: Borja Marcos <borjam@sarenet.es> To: "Brian" <ircd@wrath.com> Cc: freebsd-hardware@freebsd.org Subject: Re: 3ware stuff not ready for heavy duty useage-followup Message-ID: <200108221009.f7MA98V17043@borja.sarenet.es> In-Reply-To: <005101c12aa5$7dd36160$0201a8c0@fear.wrath.net> References: <XFMail.010821164825.nicole@unixgirl.com> <03d801c12a9e$bab359c0$6601a8c0@elitists.org> <005101c12aa5$7dd36160$0201a8c0@fear.wrath.net>
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On Wednesday 22 August 2001 02:58, you wrote: > I admit to being a dumb college kid. > > OK, the most energy I've ever seen a drive take is when it's powering up > (common sense). I can't remember seeing a drive that required more than 3 > amps to power up. 12v x 3a = 36 watts. A general rule of thumb is that > the read/write power is half of that that takes to spin the disk up. So > let's see, that would be 18 watts. > > 8 disks x 36 watts/disk ~ = 290 watts. So, she should be definitely safe > with a 400 watt power supply. It should very much definitely handle it > when running. > > Now, I've got a crappy 235watt power supply. It handles my six drives, my > dual katmai p3-550's, a pair of dual fan cpu fans, and three fans. Sure, > you can attempt to ridicule me for doing such things, but I shall ridicule > you for being impractical. It is not only a matter of watts. A 300 W PC power supply *cannot* give 25 A at 12 V. Such supplies use to have limitations. You can get 300 W adding the currents it can supply for +5 V, -5 V, +12 V and -12 V. Borja. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the messagehelp
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