Bizarre CPU fan issues

  • Thread starter Thread starter Jase
  • Start date Start date
J

Jase

Hi,

I've been having problems with my AMD Athlon XP 2000+ CPU overheating
recently so I bought a Akasa King Copper 824CU today.

I fitted the new fan and switched the machine on but before it tested the
memory the machine stopped and displayed "CPU Fan error" (or something like
it) across the middle of the screen then powered itself down. This happened
before I could access the BIOS.

I had no idea what the problem was as I connected the new cable to the same
power connector as the old fan (on the mobo). I then tried connecting the
old fan (lying loose in the system) into the mobo connector and new fan
(still on the CPU) onto a spare power connector - and it worked! This then
allowed me to get into the BIOS and I disabled "Detect CPU Fan Post" - I've
no idea what it does but I can now connect the new fan into the mobo power
supply and it works fine - so far it appears to cool the CPU by over 20 deg
C!

However the fact it detected a problem with this BIOS setting enabled
worried me. Does anyone know what the issue is and how to resolve it?

One other question... my old fan *seemed* to blow air out but the new fan
seems to suck air in - what is the correct way?
 
Jase said:
Hi,

I've been having problems with my AMD Athlon XP 2000+ CPU overheating
recently so I bought a Akasa King Copper 824CU today.

I fitted the new fan and switched the machine on but before it tested the
memory the machine stopped and displayed "CPU Fan error" (or something like
it) across the middle of the screen then powered itself down. This happened
before I could access the BIOS.

I had no idea what the problem was as I connected the new cable to the same
power connector as the old fan (on the mobo). I then tried connecting the
old fan (lying loose in the system) into the mobo connector and new fan
(still on the CPU) onto a spare power connector - and it worked! This then
allowed me to get into the BIOS and I disabled "Detect CPU Fan Post" - I've
no idea what it does but I can now connect the new fan into the mobo power
supply and it works fine - so far it appears to cool the CPU by over 20 deg
C!

However the fact it detected a problem with this BIOS setting enabled
worried me. Does anyone know what the issue is and how to resolve it?

One other question... my old fan *seemed* to blow air out but the new fan
seems to suck air in - what is the correct way?
Click to expand...


looks like your bios is looking for a certain RPM
and the new, larger fan with it's lower RPM looks like an error

that happend to me onone machine and i had to update the bios
in order not to get the low RPM error

fans generally blow in....towards the cpu
 
philo said:
looks like your bios is looking for a certain RPM
and the new, larger fan with it's lower RPM looks like an error

that happend to me onone machine and i had to update the bios
in order not to get the low RPM error
Click to expand...

Ahhhhh.... that makes sense.

Why/how do new fans have a lower RPM but maintain such good cooling?
 
Kráftéé said:
Better effeciency
Click to expand...

It could also be that the tach signal from the new fan is 'dirty' and
not being read properly in the BIOS. Also, some fans draw more current
than the header on the MB can supply, which will cause problems. In
these cases, it's best to just connect the CPU fan directly to the PSU,
as you have done.
Just set the temp alarm in the BIOS and/or run a monitoring program to
look at the temps and/or voltages, and there won't be any problem if the
fan should fail and the CPU overheats. A good one is MotherBoard
Monitor:
http://mbm.livewiredev.com/
 
Jase said:
Ahhhhh.... that makes sense.

Why/how do new fans have a lower RPM but maintain such good cooling?
Click to expand...

The one I used was physically larger than the old one...
so "pushed" more air but at a lower RPM
 
philo said:
The one I used was physically larger than the old one...
so "pushed" more air but at a lower RPM
Click to expand...

Talking about fans, my CPU fan that came with a 3GHz P4 runs at about
3300rpm (when the PC is more or less idle). At this speed it is quite noisy.
Is it possible to replace these? If so, any suggestions.
TIA
 
Talking about fans, my CPU fan that came with a 3GHz P4 runs at about
3300rpm (when the PC is more or less idle). At this speed it is quite noisy.
Is it possible to replace these? If so, any suggestions.
TIA
Click to expand...

Due to the design, incorporating the fan into a plastic shroud, it's
harder than it "could" be. You might put a resistor or series of
didoes, in series on the power leads, or take off the shroud,
carefully cuttin out the fan and leaving a flat hole where you could
attach the fan of your choice.

Alternatively you could just drill holes in the fins and attach the
fan with 4 L-brackets and screw/bolts, or just buy a new 'sink. It's
a shame that after all this time, intel still uses such a proprietary
'sink... I guess they think it looks cool.
 
Thanks for the link. Is there any info on the performance of the Intel
supplied fan (airflow, noise, etc)? I'd hate to go and spend money on a
'quiet' fan just to find it's just as noisy as the one I already have.
Click to expand...

Typically Intel uses Sanyo Denki fans,
http://sanyodb.colle.co.jp/product_db_e/coolingfan/dcfan/cooling_dcfan.html
A 3300RPM fan would be what Sanyo considers an "H" (as-in, high) speed
model. Choose same or different manufacturer's Medium or Low speed
(some manufacturers have even more gradations) model to reduce the
noise. The thicker the fan, the more air produced per RPM, the better
the airflow to noise ratio.

Depending on exactly what you're wanting to do, replace only the
original fan vs. replace whole 'sink, choose the diameter than barely
fits, as large as possible, with RPM between 1800-2200RPM. Some
people use even lower RPM fans, but considering your 3GHz CPU it'd be
good to stay near 2000 RPM, not much lower. Ball bearing fans are far
more reliable than generic sleeve-bearing models, but slightly
noisier... for utmost sound reduction choose only sleeve bearing if a
Panaflo or Papst fan.
 
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