CPU fan stopping all the time.

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My computer has CPU 2600+ processor, bought computer before 4-5 years.
Last weeks my FAN works weird, all the time it turns ON and then turns
OFF, like, it works for 2-3 sec and then 2-3 sec is still. Average CPU
temperature is 55C. Room temperature is about 22C.

Does anyone have a clue what's going on? Is it because FAN is to old?
Whats wrong with it?

Thanks ;)


Re: CPU fan stopping all the time.

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There are a couple possibilities.

A fan is a mechanical device, and it will eventually wear out.
On some kinds of expensive equipment, the maintenance manual
suggests replacing all fans every three years, before the fan
can fail. That is known as preventive maintenance.

The fan also has to get its power from somewhere. A CPU fan
typically plugs into a CPU fan header. Some of the fan
headers, have a transistor next to them, and the transistor
regulates the source of power for the fan. The BIOS may have
a feature to control the fan speed, by means of that

If there is a problem with the transistor, or with the
chip that sends the control signal to the transistor, that
can also cause the fan to misbehave.

I would start by searching for a replacement fan. Maybe this
will mean buying a complete CPU heatsink/fan assembly, so
you get something that is known to work well at cooling
your processor.

If, after installing some kind of replacement fan, the
fan still stops and starts, then the next thing to look
for is a power adapter cable. You can get a cable, with a
Molex connector on one end, and fan connector(s) on the
other end. The male fan connector goes to the new fan.
The female fan connector, sometimes having a single wire
on it, connects to the CPU fan header on the motherboard.
This allows the power to make the fan turn, come from a Molex
disk drive connector. While at the same time, the RPM signal
from the fan, is still connected to the CPU fan header.

For example, on this adapter, the red/black pair of wires
carry +12V/GND as the source of power for the fan. The
yellow/black connector is plugged into the CPU fan header
on the motherboard, and that allows the motherboard to
monitor the RPM signal (the yellow wire).



Re: CPU fan stopping all the time.

Paul wrote:
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Ummm, wouldn't it be logical to just get the adapter first? It would be half
the price (actually probably far less) than a new HSF assembly and one-tenth
the skill and time to fit. To be honest I have had many fan failures and
what Delorean is describing doesn't point to fan failure IME.

Re: CPU fan stopping all the time.

For a motherboard that old, it should be really cheap to try replacing the
Might also try cleaning the bios, unplug power cord and remove CMOS battery
jumper for 30 seconds.
Then reset everything in bios.
Really does sound like the fan has worn out.

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Re: CPU fan stopping all the time.

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You can get an adapter that connects to the standard four pin Molex
that plug into your harddrives and has a male 3 pin power connector (with a
pass through)
that will power your fan.  If there is something wrong with the transistor
that powers
your motherboard fan power circuit...this *might* solve the problem.


Re: CPU fan stopping all the time.

Thanks for your replay. Seems that fan was really out of date. I
replaced FAN and everything works fine.

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