Cheap PCs from Wal-Mart - mini-itx - 12v

Ken Chase math at
Mon Jun 2 22:54:12 EDT 2003

On Mon, Jun 02, 2003 at 03:54:37PM -0700, Alvin Oga's all...
  >hi ya ken
  >On Mon, 2 Jun 2003, Ken Chase wrote:
  >>   >we did lots of testing on that 12v dc-dc input to the  mini-itx mb
  >>   >( well, folks did all the testing and ordering of the
  >>   >( custom 12v dc-to-dc atx power supply
  >these tests were for 1-z 2-z systems .. one dc-to-dc ps for each mini-itx
  >motherboard in the stackable case-size of a standard cdrom
  >> Any numbers on the PF of these ac-to-dv (then to dc) floor-brick-with-
  >> power-cables xformers? I suspect this stuff isnt worth anything til you
  >> run it off a site-wide 12V infrastructure to get a good PF rating.
  >or one can operate like a colo ??
  >	- take 110VAC in, convert to 12V dc batteries, generate 110VAC
  >	to powerup the colo'd servers
  >or 48V dc ( like the phone systems )

totally agreed. my point was that if you dont do this, you'll lose a
fair bit in any power saved. I measured a couple laptops around the
office with that horridly-named 'kill a watt' or whatever its called
thing we ordered after someone on list suggested it - one shoddy old
laptop xformer was running at 0.45pf! Most were in .55 to .6 range.

Most PC atx ac to dc standard supplies were in .75 to .85 range. A
few of our nicer servers had 0.98 to 1.0 pf.

Furthermore, our UPS situation would be a fair bit more efficient
I suspect were we backing up a fair bit more 12 and 48V than trying
to rectify it back to AC, regardless of what losses the end systems
incur (just think - ac to dc to charge the batteries, and then in
an outtage, dc to ac back to dc. the horror!)

Furthermore, it seems to be the only way to power these low-power systems,
with DC to DC PS's - these things would probably require a 75 to 100W 
AC ATX PS for a diskless setup... Who makes those anymore - hard
enough these days to find a 250.


  >have fun

Ken Chase, math at  *  Velocet Communications Inc.  *  Toronto, Canada
Wiznet Velocet Datavaults  24/7: 416-967-4414  tollfree: 1-866-353-0363

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