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CPU fan ramps up to speeds causing the case to vibrate

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July 11, 2014 6:41:52 PM

Using a M2N68-LA (Narra3) with an AMD Athlon 64 X2 5000+ running windows 7 Ultimate 64bit.
I have ruled out the power supply as an issue by swapping out the stock PSU with a CM 750w. Normal RPM is 1886.

After about 20 minutes of being on it will begin to randomly ramp up slightly to 2500 rpm but if I turn open up a video or run any type of anti-virus, the rpm's will spike to 3500+

I have been using HWmonitor, HWinfo, and speed fan to monitor the temperature with HWmonitor and info giving me odd temperatures in the 200f at idle, and speed fan giving me temperatures of 110f at idle.

When I open a video, say the sample video provided my windows, the temp spike to 120f. Now anytime after that, the temp will go no lower than that, even if the computer is just sitting there.

Things I have done/Looked for.
-re-applyed thermal paste
-checked for bad caps

Anyone know what may be wrong?
a c 387 à CPUs
July 11, 2014 8:34:20 PM

One possibility; the BIOS is not controlling the fan speed as it should. Another is that the fan motor is not responding correctly to the voltage signal from BIOS. I'd first try replacing the cooler. Then I'd consider the MB as the problem.
Btw, if the cooler fan is vibrating the case, the case must be small with limited venting. Or the cooler isn't mounted well. The latter may even be the cause of the sudden ramp up in speed. If the cooler isn't making good contact with the CPU heat spreader, the BIOS will try to speed up the fan for more cooling.
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July 12, 2014 11:02:33 AM

clutchc said:
One possibility; the BIOS is not controlling the fan speed as it should. Another is that the fan motor is not responding correctly to the voltage signal from BIOS. I'd first try replacing the cooler. Then I'd consider the MB as the problem.
Btw, if the cooler fan is vibrating the case, the case must be small with limited venting. Or the cooler isn't mounted well. The latter may even be the cause of the sudden ramp up in speed. If the cooler isn't making good contact with the CPU heat spreader, the BIOS will try to speed up the fan for more cooling.


Alright I will replace the CPU fan, I will also check to see if the bracket is mounted properly on the mobo. This is a pre-built system from best buy. My church gave it to me to try and fix it.

Thanks for the advice, I will post again once i've tried this
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July 16, 2014 5:20:21 PM

clutchc said:
One possibility; the BIOS is not controlling the fan speed as it should. Another is that the fan motor is not responding correctly to the voltage signal from BIOS. I'd first try replacing the cooler. Then I'd consider the MB as the problem.
Btw, if the cooler fan is vibrating the case, the case must be small with limited venting. Or the cooler isn't mounted well. The latter may even be the cause of the sudden ramp up in speed. If the cooler isn't making good contact with the CPU heat spreader, the BIOS will try to speed up the fan for more cooling.


I have replaced the fan, now the temperature stays below 100f at idle. However when I start a program after awhile the temperature spikes and the fan begins ramping. The fan has been helping and can handle the ramping better, but it is still happening. So I guess this is either a problem with the motherboard supplying power to the fan or the CPU not being able to handle stress. Any solutions?
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a c 387 à CPUs
July 16, 2014 5:42:50 PM

38C is a good idle temp. But the earlier reported load temp of 98C was dangerously high. So be sure to check the load temp with this new cooler.
It would seem that the MB/BIOS is not controlling the fan speed properly. At least, that is what I gather from your explanation. But that is why we need to know the load temp when the fan begins to speed up. And it is easier for me to think in Celsius than in Fahrenheit.
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July 16, 2014 5:44:57 PM

clutchc said:
38C is a good idle temp. But the earlier reported load temp of 98C was dangerously high. So be sure to check the load temp with this new cooler.
It would seem that the MB/BIOS is not controlling the fan speed properly. At least, that is what I gather from your explanation. But that is why we need to know the load temp when the fan begins to speed up. And it is easier for me to think in Celsius than in Fahrenheit.


Ah alrighty well load temp with new cooler is 51C while idle is at 36

and it will spike RPM's at around 51C

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a c 387 à CPUs
July 16, 2014 5:53:48 PM

Those temps are great. Nothing wrong with the cooler or CPU. It would have to be a BIOS issue. I don't know how sophisticated the BIOS is in that MB, but can you set the BIOS so the CPU fan runs at full speed all the time? It will be noisy, but it would be interesting to know if the ramping up and down still happens.
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July 16, 2014 8:59:07 PM

clutchc said:
Those temps are great. Nothing wrong with the cooler or CPU. It would have to be a BIOS issue. I don't know how sophisticated the BIOS is in that MB, but can you set the BIOS so the CPU fan runs at full speed all the time? It will be noisy, but it would be interesting to know if the ramping up and down still happens.


Unfortunately no, there is no option. Something I haven't done is reset the bios via the jumper pins. I was wondering, would the battery for the bios have anything at all to do with this? Something im noticing is that the computer is unable to keep track of time while it is turned off.

edit:
Just noticed everything I wrote there seemed as if it had nothing to do with the rest. What I mean is that I read that the battery on the the mobo is in charge of the bios. So i was wondering if the fact that it can no longer keep time is a sign of the battery failing, and would that also cause problems with fan control
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July 16, 2014 9:13:27 PM

Something to add, there is an nVidia network card, single ethernet. Its a PCI card, I just took out and im stressing the system out. Its been 20 minutes with no ramping so far.
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a c 387 à CPUs
July 17, 2014 10:39:58 AM

That network card sounds like it may have been the issue, huh?
But to your other question, yes... the CMOS battery keeps the BIOS memory refreshed. If it dies or gets too weak, the time is usually the first indication you get that the BIOS has defaulted to its factory settings. If that is the original battery in that PC, it is amazing that it is still good.
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July 17, 2014 2:18:59 PM

Nah I take it back, after sometime it still spikes. Replaced the battery. still no luck.
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a c 387 à CPUs
July 17, 2014 2:51:55 PM

James Gallier said:
Nah I take it back, after sometime it still spikes. Replaced the battery. still no luck.


If removing the CMOS battery and then using the CLR CMOS jumper to reset the BIOS while the battery is out doesn't fix it, the problem may be out of our hands to fix. If you do the reset, be sure the PC is off.
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July 17, 2014 5:42:03 PM

Yea i replaced the battery and cleared the CMOS separately. The CPU cooler I got has an option to be connected to a dial that controls the speed. Just going to use that until I figure it out, if ever
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