[ale] PC power supply voltages

[Dan Lambert]

I don't have an article or link I can point you out to, but it is a well
know fact that having a low voltage to memory or processor will cause
data loss or corruption. 

It's a really fine line, but too much voltage can burn the processor or
memory circuits out by trace to trace arcing, or too low a voltage will
cause the current flow to be too high. this overloads the traces and
they burn out. 

Processors and memory really don't care about specific voltage or
current as long as it's within a comfortable range. They live on WATTS!
The trick is that to get the correct current flow at the correct voltage
that PS voltage has to be dead nuts on it! A variance of 5% is the
absolute max, and 1-2% is more like what is required.

Dan

On Fri, 2007-02-16 at 09:29 -0500, Jerry Yu wrote:
> James, that's very informative. Do you have a link or article that
> elaborates on this voltage vs. system/data integrity relationship?
> 
> On 2/16/07, James P. Kinney III <jkinney at localnetsolutions.com> wrote:
>         On Thu, 2007-02-15 at 22:34 -0500, Jim Popovitch wrote:
>         > On Thu, 2007-02-15 at 22:12 -0500, Dow_Hurst wrote:
>         > > Jim,
>         > > Can you hear any fan bearings going bad?  Has someone
>         brought in a small heater that is on the same circuit? 
>         >
>         > It's in a datacenter downtown, so I can't (yet) hear
>         it  ...and I don't
>         > feel like driving down there atm.  However an identical box,
>         right next
>         > to this box, isn't having the same issues... so I think the
>         "small 
>         > heater" issue is out of the question.  The fan speed is
>         different
>         > between the two boxes, but neither is out of range of it's
>         average over
>         > the past year.  All metrics are in spec, other than the
>         occasional blip 
>         > on the low voltage power lines.
>         
>         I would get a replacement PS in the box ASAP. Start double
>         checking the
>         logs for intermittent memory errors and non-fatal kernel
>         faults.
>         Over-voltages cause system damage. Under-voltages cause data
>         damage. 
>         >
>         > -Jim P.
>         >
>         > > Dow
>         > >
>         > >
>         > > -----Original Message-----
>         > > >From: Jim Popovitch <jimpop at yahoo.com>
>         > > >Sent: Feb 15, 2007 9:35 PM 
>         > > >To: Atlanta Linux Enthusiasts <ale at ale.org>
>         > > >Subject: Re: [ale] PC power supply voltages
>         > > >
>         > > >On Thu, 2007-02-15 at 20:44 -0500, Scott Castaline
>         wrote: 
>         > > >> Jim Popovitch wrote:
>         > > >> > I've got a box where lm-sensors shows the +3.3
>         voltage going up and down
>         > > >> > between 3.39 and 3.41.  It jumps to 3.41 every ~1.5
>         hours and shortly 
>         > > >> > thereafter drops back to 3.39 (which has been it's
>         normal voltage for
>         > > >> > the past year or so).  A second box right near it
>         isn't experiencing
>         > > >> > this behavior, which started at 2pm today, and there
>         are no other 
>         > > >> > indications of any problems.  How concerned should I
>         be?
>         > > >> >
>         > > >> I don't think that it's a problem yet since the
>         fluctuation is within 5%
>         > > >> of it's nominal voltage of 3.3. But it could be an
>         indication of
>         > > >> something is strarting to go, but I've seen older power
>         supplies do that
>         > > >> and last for several months to a couple of years.
>         > > > 
>         > > >It gets worse. :-(
>         > > >
>         > > >-12V is -14.91 (outside range [-10.80:-13.18])
>         > > >VBat is 0.03 (outside range [2.40:3.60]) <- WTF is VBat?
>         (it's a server)
>         > > >VCore is 1.35 (outside range [1.93:1.93])
>         > > >V5SB is 5.16 (outside range [4.86:5.14])
>         > > >
>         > > >
>         > > >-Jim P.
>         > >
>         > >
>         > > No sig.
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>         James P. Kinney III
>         CEO & Director of Engineering 
>         Local Net Solutions,LLC
>         770-493-8244
>         http://www.localnetsolutions.com
>         
>         GPG ID: 829C6CA7 James P. Kinney III (M.S. Physics)
>         <jkinney at localnetsolutions.com>
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