On 23 Dec 2001, at 12:44, Paradox wrote:
> I don't think I made the "Thermal Monitor" feature
> clear enough. From what I've read at Intel's
> website, I believe it is built onto the P4 chip,
Yes, most current processors have a thermistor on chip & some
means of signalling the die temperature through the pin array.
> independent of the motherboard except that the
> motherboard has to activate it at boot.
OK, I looked at the Intel documentation. (Specifically the document
24988701.pdf which is the datasheet for the 478 pin P4.) The P4
does have an "auto" thermal management mode _in addition to_
the "manual" mode similar to other current processors. The manual
mode allows BIOS to set the threshold temp & throttle ratio (in
12.5% steps), the auto mode fixes the threshold temp (at an
unspecified value - possibly dependent on processor speed and/or
stepping) and also fixes the throttle ratio ("duty cycle") at 50%.
Intel claim that "auto" mode is required to keep within spec but this
is obviously garbage. The same paragraph states that thermal
throttling will never occur in a properly designed system unless
ventilation fails for some reason.
There is a pin signal to show thermal monitor active, and the info is
also available in P4-specific processor registers.
One interesting point - the Intel processor technical spec states
that, for the heatsink/fan provided with the retail boxed product, the
temperature of the CPU fan inlet air should not exceed 40C (104F).
If it does not exceed 40C, it is highly unlikely that thermal throttling
is active. Measure the inlet air temperature 1/3 of an inch above the
centre of the CPU fan.
> In any case,
> the BIOS menu that I have access to on a
> Intel D850GBC is not exactly verbose...it has nothing
> letting me change timing settings on any piece of
> hardware, and nothing about CPU throttling.
Yes, I've noticed that Intel branded mobos tend to have BIOSes
with most of the interesting parameters masked out. That's one
reason I tend to prefer mobos from other manufacturers - I like Abit
& Asus.
>
> And I definitely do not want to deactivate
> Thermal Monitor and simply ignore cooling
> problems...that would likely cause damage
> to my CPU.
You will get _severe_ instability (which will go away when the
processor is properly cooled) _long_ before you get any sort of
permanent damage. In fact the Intel P4 CPU (like most others, with
the exception of Athlon & Duron except the new Athlon XPs) also
has a temperature cutoff to protect the CPU from a failed cooling
fan by shutting down completely if its temperature becomes
dangerously high. If the trip is activated, the processor will stay
down until reset. I've never seen a BIOS which allows this safety
feature to be disabled.
>
> For cooling, in addition to the power supply,
> I have a case fan in the bottom front that
> is pulling air in, a fan on the CPU heatsink
> (the one provided by Intel), and a case fan
> next to the cpu pushing air out. There is
> also a weak 5.25" HD fan pulling air in
> from the front.
That's very similar to the Athlon system with the reversed cooling
fan I was having trouble with last week. The problem was that the
PSU & rear case fans were conspiring to draw hot air into the CPU
fan inlet :(
Adding an extra case fan dropped the case temp by ~10C without
affecting the CPU temp by more than 1C. Presumably the part of
the mobo where its thermistor is located was getting the benefit of
the extra cooling. Taking that extra case fan out but reversing the
PSU fan - so that all the case & PSU fans were blowing through
the case from front to back - dropped the CPU temp by ~12C and
kept the lower case temp.
Regards
Brian Beesley
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