Is this true?

  • Thread starter Thread starter amanda
  • Start date Start date
A

amanda

If a cpu is not hooked up to a fan and heatsink for
more than 5 seconds(with power on) it will overheat
and the core will break down.
 
amanda said:
If a cpu is not hooked up to a fan and heatsink for
more than 5 seconds(with power on) it will overheat
and the core will break down.
Click to expand...

Not true. Many of the most recent processors are protected,
and have a signal called THERMTRIP. That signal is supposed
to be connected so as to turn off the computer power. The
P4, the Athlon64, the Core2 Duo, are all examples of processors
that are protected.

There are some older processors, that are missing a protection
feature. My Nforce2 AthlonXP motherboard, has a separate 8 pin
chip added to it, and it monitors the thermal diode inside the
processor. So it is supposed to be protected. The AthlonXP by
itself, cannot turn off the power. It is possible there are some
older processors, where protection is harder to arrange (as I
don't know if the entire Athlon family, officially has thermal
diodes inside or not). Some older motherboards that took Athlon
processors, only had a thermistor in the CPU socket, and that
cannot respond fast enough to save the processor. The thermistor
method relied on software to implement the shutdown (via the
hardware monitor chip and its low sampling rate readout).

I would say, generally speaking, if you go to the computer store
*today* and buy a computer, all of them should be protected against
overheat. (I'm not counting stores selling really old stock :-) )

Would it protect the processor if you tried it 1000 times ?

I cannot answer that one :-)

Paul
 
If a cpu is not hooked up to a fan and heatsink for
more than 5 seconds(with power on) it will overheat
and the core will break down.
Click to expand...


No it's not true, but it could be.

You're trying to say something very specific when there are
several variables such as which CPU, and what "hooked up"
means.

In general, if you have a heatsink properly installed but no
fan, (including no duct with a fan at the exhaust like many
OEMs might use), it will always survive far longer than 5
seconds, would gradually overheat after a few minutes or so.
At that point, some would throttle to a lower speed, but
either way it would become instable and the operating system
or other software/bios menu/whatever would crash. If it
continued to heat up further and the system was newer, it
would shut off. If the system was older, continuing to run
in this state, after it had already crashed if it were left
like that overheating for a long time, it would tend to
cause damage many minutes later, but again it depends on
variables like how well the system case was cooled, what
peak temp it actually attained.

If there is no heatsink on it at all, yes it will probably
be damaged if turned on from cold-off state. "Maybe" if you
have a modern CPU with integral sensor and shutdown, you
might get lucky and it wouldn't be damaged before it could
shut off, but it is still quite possible because the
shutdown circuit is not designed well enough to cover
situations where the heat goes up as rapidly as it can
without any heatsink at all on it, that is just too fast a
rise in temp and the CPU can heat unevenly which will pop
off the heat spreader and crack the core.

In general if you didn't have a heatsink and fan on for 5
seconds and had tried to use the system, the CPU should be
set aside as an unknown variable until it can be tested in a
known working system (if the system it was in was not
working at this point).
 
amanda said:
If a cpu is not hooked up to a fan and heatsink for
more than 5 seconds(with power on) it will overheat
and the core will break down.
Click to expand...

VERY true and probably a lot shorter than 5 seconds.
 
Paul said:
Not true. Many of the most recent processors are protected,
and have a signal called THERMTRIP. That signal is supposed
to be connected so as to turn off the computer power. The
P4, the Athlon64, the Core2 Duo, are all examples of processors
that are protected.
Click to expand...

I tell you what if the above statement is true and you have one of
the above cpu's in your pc, you try it once and get back to us and
tell us what happened. If you are not will to do so just say that
if a heat sink is not on the cpu when pc is switched on the cpu
is dust.
 
If a cpu is not hooked up to a fan and heatsink for
I tell you what if the above statement is true and you have one of
the above cpu's in your pc, you try it once and get back to us and
tell us what happened. If you are not will to do so just say that
if a heat sink is not on the cpu when pc is switched on the cpu
is dust.
Click to expand...

You seem very sure he is wrong? The above statement is true. This should set
you straight...
http://video.google.com/videoplay?docid=5393904704265757054
 
amanda said:
If a cpu is not hooked up to a fan and heatsink for
more than 5 seconds(with power on) it will overheat
and the core will break down.
Click to expand...

Assuming you are talking about a modern CPU then I don't personally believe
the 5 second number is true. I've read other comments about how the cpu
might react to getting too hot, and I'm sure how it reacts (i e. reduces
speed, cuts out or permanently dies) probably depends on the manufacturer
and the specific cpu.

* To be honest is it worth the risk? Play safe and don't go there. Don't run
it without a heatsink and fan. *

Older cpus that were developed for just a heatsink and no fan should be more
resilient to temperature but won't be anywhere near as fast.
 
darklight said:
I tell you what if the above statement is true and you have one of
the above cpu's in your pc, you try it once and get back to us and
tell us what happened. If you are not will to do so just say that
if a heat sink is not on the cpu when pc is switched on the cpu
is dust.
Click to expand...

THERMTRIP:

Section 5.2.5 page 83. A little more text on page 72.
I can dig up more examples. The feature is there.
This sheet is for a 600 series P4 in LGA775.

ftp://download.intel.com/design/Pentium4/datashts/30638203.pdf

Paul
 
Paul said:
THERMTRIP:

Section 5.2.5 page 83. A little more text on page 72.
I can dig up more examples. The feature is there.
This sheet is for a 600 series P4 in LGA775.

ftp://download.intel.com/design/Pentium4/datashts/30638203.pdf

Paul
Click to expand...

This doc is a lot fatter (9MB). Section 5.3.1.1 and page 46 in
general, address what to do when THERMTRIP is asserted. This
is for a PIII processor. But references to THERMTRIP go back
even further than that.

http://www.intel.com/design/pentiumiii/designgd/27367604.pdf

Paul
 
If a cpu is not hooked up to a fan and heatsink for
more than 5 seconds(with power on) it will overheat
and the core will break down.
Click to expand...

I can personally attest that I killed a perfectly good Athlon 900mhz
chip that way. It was closer to 3 seconds.

Supposed thermal protection or no. It is not a wise risk.
 
You seem very sure he is wrong? The above statement is true. This should set
you straight...
http://video.google.com/videoplay?docid=5393904704265757054
Click to expand...
That's an overclocked AMD processor. When something is overclocked
and missing it's heatsink, it can heat up much faster than the
temperature sensor can react. The result is that the chip will fail.
The video authors are also known to push things as far as possible
without regards to product safety. While these failures are more
spectacular than normal, they are caused by not abiding by
specifications.
 
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