Re: OT-Odd (to me) computer failure

According to Wild_Bill <wb_wildbill@xxxxxxxxxxxxxx>:
There is so much woodoo going on in a PC that almost anything can cause
serious problems.
Many motherboard failures are related to CPUs overheating, commonly due to
dust build-up in the heatsink fins and the fan blades themselves (stalling
the CPU fan, particularly those small fans).
I've seen paper stickers on the bottom of CPUs turn tan/brown in color, from
clogged-failed CPU heatsink fans.

Agreed. Another possible source of problems is the power supply
connector. If the current is on the high side, it will eventually
overheat a pin or two, and perhaps even turn the solder joint on the
board into a cold-solder joint. Anyway -- glitches from the pin going
high-resistance can cause corruption of disk sectors as they are
written. I've seen this happen on an AT&T UnixPC (68010 CPU, not an
80x86). Depending on which pin you get different problems. One pin
powers the system RAM, another the disk controller chips, another pair
the disks themselves, and yet another the built-in monitor (in this
case), resulting in strange dancing text on the screen. :-)

My new machine has 3 each, (80mm) 3" fans.. 1 in the PSU, 1 on the case and
1 on the CPU heatsink. I've seen CPU fan/heatsink combos in stores that
utilize the 3" fans now, instead of the troublesome small ones (about
1-1/2"). The better grades of fans have 2 ball bearing assemblies in them.

The Sun Fire 280R which I just got has three 5" fans (one for
the PCI cards, one for the two CPU modules, and one for the DIMMs
holding the (up to) 8 GB of RAM.

In addition to this, there are two hot-swappable power supplies
with two 3" fans each. This is *not* a quiet machine to keep in the
bedroom running 24/7. :-)

Many motherboards have protective circuits under the physical location of
the CPU to detect overheating, which should shut the machine down. Some PC
manufacturers actually produce machines with that feature disabled.
The temp sensing circuits on the motherboards and in PSUs are supposed to
make the fans run faster as temps rise, and/or slow the CPU clock down to
reduce heat generation.

The machine in question above is designed to live in an air
conditioned machine room, so it runs the fans full speed all the time.
But it does have temperature monitoring. Currently 91 F in the box
itself, and 131 F in each CPU. (And they don't start to complain until
they reach just below the boiling point of water. :-)

[ ... ]

When I've had that case open for changes, there was no significant dust
residue anywhere (despite a nasty operating environment) that would create
problems. The filter gets furry, not the heat-generating/dissipating
components.
I utilize the case fan pushing filtered air into the case, which keeps the
media drives clean (as opposed to exaust fans sucking room air in thru the
drives).

I've got a rack-mount chassis with a built in filter in the shop
ready to control the CNC Bridgeport once I finish some conversions.
(The original LSI-11 based controller has severe electronics
Altzheimer's. :-)

I've seen pics of liquid-cooled CPU heatsinks, machined (milled) from blocks
of copper, for use by CPU overclockers that pump ice water thru the blocks.
Other experimenters have used peltier coolers for CPU heat.

And one machine which I have is quite interesting. It uses heat
pipes to carry the heat away from the CPU to a heat sink and fan
assembly high on the back panel. This is one of the "Shuttle" Intel
boxes designed for the gamers who live by overclocking their systems.
It is a "Shuttle" -- a nice compact case, but with only one PCI slot,
and one for an AGX card.

Enjoy,
DoN.

--
Email: <dnichols@xxxxxxxxxxx> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
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