MS said:
Hello, I have a P 4 3.2 E (prescott) with air cooling by a Intel C91249
Socket-478 Copper Core Cooling Fan, P/N: C91249-002 / C91249-003. Now,
the fan is supposed to run variable, slow in low temps. and fast in high
temps. The problem is that in 37ºC of cpu temperatura, the fan runs at
2500 rpm (max.). It should run slower! This is verifyed in BIOS. Are
there any configuration missing? Will the instalation of the chipset of
the mainboard help?
System
Windows Vista 32
Asrock P4i65G
1G DDR~
The CPU fan is connected to the mainboard
Thanks in advance
Manuel
The Intel fan may have a thermistor inside the
hub of the fan. It senses the computer case
air temperature (not the CPU temperature itself).
The thermistor gives the fan a temperature sensitive
speed characteristic. The reason Intel set it up
that way, is to make the fan compensate for a hot
room. If the room gets hot, Intel makes the fan
work harder, in order to keep the CPU cool.
Since the fan itself is not in contact with the CPU,
they cannot make the fan directly measure the CPU
temperature. So they sensed the case air temperature
instead.
If you take the side off your computer case, you
may notice the Intel fan slows down. That would be
because you've let the warm air out of the computer
case. If that happens, it means there is not
sufficient airflow through the computer case, to
keep the case air temperature down. So the CPU
fan screams in protest, that the case cooling is
not sufficient.
To fix that, you'd either put a better exhaust
fan on the back of the computer case, or expand
the intake vent area, so that there is less
resistance to airflow. (I had to open up vent
area on the front of my Antec Sonata, to get
better cooling.)
In addition to the Intel thermistor, the motherboard
may also exert some control. Some motherboards have
the ability to vary the voltage fed to the fan. So
that can be used to make the fan run slower as well.
Not many motherboards include control of all the fans.
Only a few Dell/HP type machines have all fan headers
with voltage control. My current Asrock board, that
I'm typing this message on, has no voltage control
options for any fan header.
My suspicion is your case air is too hot. If the
room temperature is 25C, a well cooled computer
case internal air temperature, would be 32C (a
7C rise).
Paul
