Thermal shutdown too early?

  • Thread starter Thread starter Sla#s
  • Start date Start date
S

Sla#s

Sorry if this is a bit OT but I can't find where to ask this question
anywhere but here...

I have a Pentium M in a fanless heat sink cooled Media PC system. By spec it
should be able to run up to 100 degrees C (With a shutdown at 125) but it
keeps shutting down when it
reaches only 68 degrees C. It will do this if CPU usage goes above 35 to
40%.

The thermal protection is "disabled" in the Phoenix Award BIOS
(But it is of note that the highest of the un-enabled trigger figures in the
BIOS is 68 degrees).

Is there anywhere else I could look for a thermal trigger, some other way to
disable it or raise the figure to a more usable one?

System:
Win XP Home SP2
Motherboard LV-675
CPU Pentium M 1.73GHz

TIA
Slatts
 
Recheck your specs. 100 degrees C is 212 degrees F. I don't know of ANY
electronic equipment or device that will run at that temperature. I think 68
C is a normal shut down point, and that's 154 F..
 
Recheck your specs. 100 degrees C  is 212 degrees F. I don't know of ANY
electronic equipment or device that will run at that temperature. I think 68










- Show quoted text -
Click to expand...

Water "boils" at 100 degrees C. Would not want that Media PC in my
entertainment unit (it may melt the "plastic.")
 
smlunatick said:
Water "boils" at 100 degrees C. Would not want that Media PC in my
entertainment unit (it may melt the "plastic.")
Click to expand...

No, honestly it's designed to get that hot!
See the Pentium M specification at:
http://www.intel.com/support/processors/mobile/pm/sb/cs-007971.htm
Most other chips are limited to between 60 and 75.

A bit more research though has revealed that although the Pentium M can get
to 100 degrees the LV-675 motherboard is limited to 60!

I will have to find some way of silently cooling the other chips on the
motherboard - I am currently looking at some small heatsinks that can be
glued to the small chips on it. I will have to hope the heat pipe system on
the CPU keeps too much heat from going down into the board.

What I don't get is why a 100 degree chip is fitted to a 60 degree board!
It's like making a fireplace out of newspaper!

Slatts
 
Amazing but not startling. The processor can withstand 212 degrees F. But,
that is only one component.
Boards have many components very few of which can withstand 212 degrees..
 
Sla#s said:
No, honestly it's designed to get that hot!
See the Pentium M specification at:
http://www.intel.com/support/processors/mobile/pm/sb/cs-007971.htm
Most other chips are limited to between 60 and 75.

A bit more research though has revealed that although the Pentium M can
get to 100 degrees the LV-675 motherboard is limited to 60!

I will have to find some way of silently cooling the other chips on the
motherboard - I am currently looking at some small heatsinks that can be
glued to the small chips on it. I will have to hope the heat pipe system
on the CPU keeps too much heat from going down into the board.

What I don't get is why a 100 degree chip is fitted to a 60 degree board!
It's like making a fireplace out of newspaper!

Slatts
Click to expand...

You got that number from the datasheet on the Commell site.
ftp://ftp.commell.com.tw/Public/Datasheet/SBC/LV-675.pdf

"Operating within 0~60 centigrade"

That is an ambient temperature spec, for the air around
the motherboard. Such a spec might still make some assumptions
about cooling, such as so many LFM (linear feet per minute) across
the surface of the motherboard or whatever. That is not the melting point
of the socket material.

I went to the Pentium-M portion of the Intel site.

http://developer.intel.com/design/mobile/pentiumm/documentation.htm

This one looks interesting. It is Intel's instructions to companies
providing sockets. Page 36 lists the operating range for the socket,
of 0C to 105C, presumably consistent with a laptop kind of application.

"Intel Mobile Processor Micro-FCPGA Socket (mPGA479M) Design Guidelines"
http://developer.intel.com/design/mobile/applnots/298520.htm

If you look at the socket, it may have a manufacturer name on it,
like Foxconn or Lopes. You may be able to track down what they spec
for the operating temperature range for the socket. You'd need a
part number off the socket, if one is visible.

In my mind, it still remains a puzzle, where 68C comes from.

The processor datasheet itself, provides more thermal info.

THERMTRIP, which is the hardware protection feature that shuts
off the power supply, is set to 125C on the Pentium M 90nm.
THERMTRIP uses a diode on the processor die, and is managed
by the processor itself. The board designer connects it into
the logic chain that controls PS_ON#, on the ATX power connector,
and that is how the supply gets shut off on an overheat.

PROCHOT, the throttling temperature, is set at 100C Tjunction.
The internal instruction execution rate is reduced if that
point is hit, and performance drops. THERMTRIP should
only be needed, if the heatsink falls off or fan stalls.
Normally, throttling would be enough to prevent the temp
from shooting higher than 100C.

So your 68C number remains a puzzle to me, unless the actual spec
for the socket material, is inferior to the Intel suggested 105C
number. But 105C is needed for things like laptop applications,
so I don't see a point in cutting corners. With a throttle temp
of 100C, it looks like the socket and processor were designed
for each other.

I'd contact Commell tech support and see if they have an
answer to the puzzle.

Paul
 
Back
Top