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Fan runs high at low temp - low at high temp

Forum CPU & Components : Other Components - Fan runs high at low temp - low at high temp

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jjclark86   09-20-2008 at 03:46:38 PM

Really weird problem that I haven't seen on any of the other threads. My CPU fan kicks into high gear when the CPU temp is low, then goes into low speed when the temp rises. At idle it runs about 4600 rpm. If the CPU heats up, even just a little, it cuts back to 1200 rpm. Anything that causes the CPU to heat up will do the trick - running intensive programs . . . I've even opened the case and turned a hair dryer on it for a few secs.

This effect just cropped up recently with the lower Fall temps in the house. I haven't modded/overclocked the cpu. The fan does not need to be at high/takeoff speed. It got through the warmer summer temps without ever needed to kick up.

I've tried using SpeedFan to control it, but the configure/speeds tab shows up blank. Most of the other tabs (including temperature and speed reporting) do have data. I also see no place in the BIOS to control fan speed (or even mention fans).

HP Pavilion m9200t

Any ideas?

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RavenXE   09-20-2008 at 04:16:28 PM
- 0 +


Well try clearing the cmos and if it doesn't work maybe it's a deffective PWM on your motherboard or the tachometer in your fan.... so try changing the fan.

Hope it helps

Reply to RavenXE
Hellboy   09-20-2008 at 04:19:04 PM
- 0 +

jjclark86 wrote :

Really weird problem that I haven't seen on any of the other threads. My CPU fan kicks into high gear when the CPU temp is low, then goes into low speed when the temp rises. At idle it runs about 4600 rpm. If the CPU heats up, even just a little, it cuts back to 1200 rpm. Anything that causes the CPU to heat up will do the trick - running intensive programs . . . I've even opened the case and turned a hair dryer on it for a few secs.

This effect just cropped up recently with the lower Fall temps in the house. I haven't modded/overclocked the cpu. The fan does not need to be at high/takeoff speed. It got through the warmer summer temps without ever needed to kick up.

I've tried using SpeedFan to control it, but the configure/speeds tab shows up blank. Most of the other tabs (including temperature and speed reporting) do have data. I also see no place in the BIOS to control fan speed (or even mention fans).

HP Pavilion m9200t

Any ideas?



Reset the bios by removing the battery whilst unplugged from the mains

Clean any dust from the heat sink...

Download the latest bios and flash the machine...

Is it a socket 775, if so make sure all 4 pins on each corner are pressed home...

Could be a faulty ic for fan control - never seen one go but then again.. The fan could be relaying faulty readings too,, try replacing the heat sink and fan with a decent unit which will fit inside the case...

Thats what i would do first....

Reply to Hellboy
jjclark86   09-20-2008 at 04:20:10 PM
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I've cleaned everything out. The speed reporting on the fan seems accurate. SpeedFan shows it jump up when the fan goes into high gear.

Is it possible that the fan leads are reversed? That is, when the machine asks for low speed, it actually sends a signal for high?

Reply to jjclark86
jjclark86   09-20-2008 at 04:20:47 PM
- 0 +

I've also reset the BIOS and downloaded that latest

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Hellboy   09-20-2008 at 04:29:55 PM
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jjclark86 wrote :

I've also reset the BIOS and downloaded that latest




The only way you can tell is to replace the complete fan and heat sink


Pop to your local pc shop-- get a decent one and change it ... see what happens.

------------------------------ jennyh wrote: AMD break-even Q4 2009. *Gauranteed*

 

Reply to Hellboy

Grimmy   09-20-2008 at 04:33:16 PM
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Generally the power pin connector only goes on one way for the header on the MB. Unless HP got the wires mixed up, it should not work at all if they messed that up.

 

If the HP PC is still under warranty, you might as well call them and tell them about it.

 

In the bios, Smart Fan would be what is controlling CPU fan speeds. Since it's an HP PC, it's really hard to say what settings you have for the bios.


Message edited by Grimmy on 09-20-2008 at 04:33:57 PM
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jjclark86   09-20-2008 at 05:07:20 PM
- 0 +

Called HP about it yesterday. They were spectacularly unhelpful. It's still under warrenty so their fallback was to have it shipped back for a couple weeks were they'd bring it back to factory spec including wiping the HD.

I'll do this as a last resort

Reply to jjclark86
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