In hot water (really hot air, but that's something else)

[Kevin O'Gorman]

It's a 400 watt supply (new).  The box contains
  Motherboard (new) with integrated:
    NICs (2)(new)
  Adaptec 39160 SCSI controller (new; downstream from CPUs)
  Floppy drive (Sony, new, upper part)
  1GB Jaz drive (unknown age; upper part, downstream)
  Old old 1GB IDE drive (unknown age; lower part, downstream)
  36GB IBM SCSI drive (fairly new; lower part)
  total of 7 fans (all new)

This does not seem like a heavy load.  There's just the one add-in card.
None of this stuff is upstream in the airflow from the CPUs.

/var/log/messages has nothing of interest to report.  I see a regular
sequence of crond log entries leading up to the moment I told the system
to go down.

As I was taking the above inventory, I did notice that some of the
ribbon cables were flat against the intake fan one the power supply.
The supply may have been overheating; perhaps it can signal to the
motherboard?  Anyway, I've tied them back now, and we'll see what happens.

++ kevin


-- 
Kevin O'Gorman, PhD  (805) 650-6274  mailto:kevin at kosmanor.com
Permanent e-mail forwarder: mailto:Kevin.O'Gorman.64 at Alum.Dartmouth.org
Permanent e-mail forwarder  mailto:kogorman at umail.ucsb.edu
Web: http://kosmanor.com/~kevin/index.html

On Sun, 1 Sep 2002, Net Llama! wrote:

> I don't think this is an overheating problem.  Especially since the CPUs 
> should speed back up once they cooled down.
> 
> How much wattage is the power supply?  What other hardware do you have 
> in this box?  Are all the components brand new?  Have you looked at your 
> messages log for errors?
> 
> Kevin O'Gorman wrote:
> > I may have done something foolish.  Nothing new.  But I cannot tell
> > for sure, and I could use advice.
> > 
> > I bought parts to make a dual-Xeon machine, with DDR memory.  It was
> > to be my main server at home.  It's up and running, partly, and it's
> > about as fast as I had hoped.  But after a while, it suddenly becomes
> > S U P E R    S L O W.  Think PC/XT speeds.
> > 
> > I understand that Xeon CPUs have heat sensors, and that when they
> > detect overtemperature, they slow down.  That's good as far as it
> > goes, but I don't see why they would be overheating.
> > 
> > The chassis is a tall tower (with a sort of upper part and lower
> > part).  The upper part has the disk drives and power supply, and
> > is separated from the lower part by a piece of sheet metal with
> > a hole big enough for all the cables I'll need.  The lower part
> > has the motherboard with CPU's, my one add-in card (SCSI controller:
> > adaptec 39160) and a mess of fans.  
> > 
> > The power supply has an exhaust fan, and there's quite a big
> > auxiliary exhaust fan just above it.
> > 
> > In the lower bay, there's a similar big exhaust fan, both CPUs
> > have wind-tunnel head sinks with fans pointing towards the back,
> > and I've put and additional two fans pulling air in the front
> > and aimed at the CPUs.  When I touch the heat sinks, there's no
> > noticeable warmth at all, even right down by the CPU chip.
> > 
> > This whole afair is sitting on my table, next to my monitor.
> > The first two times it went into molasses-mode, all the skins were
> > on it.  I've got one side exposed now, and nothing bad has happened
> > so far, but sometimes it has taken 18 hours of running or so for
> > mollasses to begin.  This morning it only took about 1/2 hour.
> > 
> > The room is not particularly warm, though it's not air-conditioned.
> > I wouldn't run the A/C right now if I had it.
> > 
> > Any ideas?  Is there something besides heat that could make these
> > babies slow down?  Is there something I could test?  Can I make
> > them speed up without a reboot?  Is that a good idea?
> > 
> > Was it foolish of me to gear up for Xeons?
> 
>