motherboard problem

cdtplug

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May 5, 2005
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hi i have an asus a7n266-vm motherboard with an amd duron 1300 cpu.the cpu heatsink and fan has stopped working. the computer boots up then switches off after a minute or so because of the cpu overheating, i bought a new heatsink and fan and fitted these but it still would not work. i tried connecting the cooler to the case fan connector but this still did not work.

i have tried what i thought was the faulty cooler in another pc and this works fine.

any help appreciated in solving this problem

thanks

chris
 

slvr_phoenix

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Dec 31, 2007
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Weird. It sounds like the CPU fan header has died. If you had a voltmeter you could check that to be sure. Otherwise you could try the generic things like blowing away dust and looking for bad capacitors. If that doesn't work you could try getting more specific like lightly sanding your CPU fan header posts, hooking the CPU fan up to a different header, or even getting a fanless heatsink so that the CPU won't overheat.

Other than that, I can't think of anything to suggest, other than a new motherboard.

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pat

Expert
Connect the fan to a working PSU header (might have to cut and connect wire for that) to have it run. There is maybe a way to bypass the fan speed check by BIOS. use it and disable that feature in BIOS. so your BIOS will let the system boot even if it dont sense the fan running.. just like if you were water cooled..

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Crashman

Polypheme
Former Staff
Many boards won't operate long if they don't detect a CPU fan speed signal.

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slvr_phoenix

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Dec 31, 2007
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So which wires are for power and which one is for the RPM monitor? (In other words: How do you splice your CPU fan wires to a molex connector for power in such a way that your mobo can still monitor the speed?)

<pre><font color=purple><i>Jesters do oft prove prophets.</i> -Regan in
King Lear (Act V, Scene iii) by William Shakespear</font color=purple></pre><p>@ 187K -> 200,000 miles or bust!
 

pat

Expert
Usualy an option in BIOS... to disable fan check, as if you were running it watercooled.

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slvr_phoenix

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Dec 31, 2007
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For a modern system, sure. What about older systems without that option though? I'm just curious myself (though I have no actual need for the information), but also thinking that cdtplug may need the info too. And if not cdtplug, then maybe someone else who finds this. You never know. It's like the molex rewire to undervolt a fan. It's weird enthusiast knowledge that most people never need but is still interesting anyway.

I don't have a CPU HSF handy to look at, but it's only three wires and I'm guessing that there's probably a black wire for ground. So one of the remaining two is fan power and the other is the RPM info. No?

<pre><font color=purple><i>Jesters do oft prove prophets.</i> -Regan in
King Lear (Act V, Scene iii) by William Shakespear</font color=purple></pre><p>@ 187K -> 200,000 miles or bust!
 

Crashman

Polypheme
Former Staff
The ground wire and the wire next to it are power, the third wire is fan detection.

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endyen

Splendid
I had a super socket 7 mobo, with fan speed detect. In bios, there was an option to ignore. I sure hope there aren't any newer boards that are less capable. It used an AT psu.