CPU Fan Error - what if I just use the chassis plug?

Hi all,

I completed a build of a new system last night: It's an ASUS P8Z68-V LE with a 2500K. I encountered just one problem.

When the stock cooler is connected to the CPU_FAN pins, it simply refuses to work. In BIOS, there's the CPU Fan Error and when I watch the temp in the uefi, it rises pretty steadily.

So we tried plugging the cooler into the chassis fan pins, and that did the trick. It seems to be keeping the cpu at a reasonable temperature. I understand that the CPU_FAN pins are specifically designed to control the speed of that particular fan. We also allowed the bios to skip over the error without requiring further action.

My questions are these:
Is there any real danger in doing this?
Is it likely the wear the fan out quicker?
Is there any way to make the chassis port ACT like the CPU_FAN port in adjusting the speed?
Is there any way updating bios, flashing the cmos, adjusting power cables, or something like that would actually fix this issue?

Frankly, is this a known motherboard error?

I'd appreciate and and all input. Thanks!
4 answers Last reply
More about error chassis plug
  1. I'd check here:
    it might be a bios fix or a RMA matter. You are definitely not getting what you paid for though. You've got a good board and should be able to use every socket on it.
  2. Did the CPU fan run at all when connected to the right pins? Sometimes the Cool'nquiet feature runs the fan too slow at startup when the machine is cold. I had to disable the feature on an Asus board to prevent having to hit F1 every time I booted from cold...
  3. Did the CPU fan have 4 pins? or 3? Pin 1 is Ground, 2 is 12V, 3 is speed or direction sensor, and 4 is PCM (Pulse Code Modulation) which mean the 12V is swithced on and off and the On time controls speed. More on time more speed. The CPU connector on MB is 4 pin and may be set up for PCM to fan and fan has no 4th wire. Standard intel fans have 4 wires. That meas pin 2 does not have 12V during PCM operation. In Bios advanced mode under "Monitor" you can set the CPU fan and Cassis fan.

    Ok OK. PWM, Pulse width Modulation. PCM is more complidated for digital data like the time code on WWV or RC com to remote vehicle or Predator.
  4. The CPU fan was not working at all when connected to the CPU_FAN pins.

    I've got my hands on a spare i5 stock cooler, so we may try it to see if for some reason it could be the fan itself, or the wires, that's the problem.

    So far, however, things have been running fine with it connected to a 4-pin chassis connector.
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