3 Replies Latest reply on Feb 12, 2010 12:12 PM by spearson

    DQ45CB, QST off, fans speed problem


      I have QST turned off, but the fan speed is still controled by the bios.  Fans (case and cpu) rev up to 800rpm or so and down to 0rmp then to 800rpm then down to 0rpm.....


      Am I missing another setting to allow the fans go full speed?

      Is there any way to control the fan speeds with QST on?

        • 1. Re: DQ45CB, QST off, fans speed problem

          In the BIOS, there's an option for System Fan Control, I believe it's under the Advanced heading, then Boot Configuration.  There are three options there:  Disabled, Always, and Next Boot.  I'm pretty sure Disabled is default, I set it to Always (which means it detects the fans on every boot).  That usually solves the revving fans.

          • 2. Re: DQ45CB, QST off, fans speed problem

            Upgraded to the latest BIOS CB0111 and still no change.

            • 3. Re: DQ45CB, QST off, fans speed problem

              Please provide me with a more detailed description of what is happening (how long it is on, how long it is off, etc.). I can think of a number of issues that could cause a response like this...


              How did you "disable" QST? Did you go into MEBX and turn off the QST subsystem completely? There is a parameter in BIOS setup that specifies whether, during system boot (BIOS POST), the BIOS/QST should perform a fan (re-)detection operation. This parameter has 3 settings, Disabled, Next Boot and Always. The Disabled setting DOES NOT mean that QST is disabled; it only means that the fan (re-)detection operation will not be performed during BIOS POST. If QST is enabled and this parameter is set to Next Boot or Always, the fan (re-)detection is going to be performed (and, after doing so, if the parameter was set to Next Boot, it will be reset to Disabled). Note that leaving the parameter at the Always setting is not recommended; doing so could result in a loss of any notification of a fan failing.


              The first recommendation that I would make is to have a fan detection performed. Go into BIOS Setup, set this parameter to Next Boot and exit BIOS Setup saving changes. If this fixes your problem, it means that QST thought that a fan was previous present and working that is currently not. When QST sees that a fan has failed (stalled), it attempts to get this fan working again (overcome its inertia) by sending large pulses of power to it. On motherboards that have two fans controlled by a single fan speed controller, the operation to restart a stalled fan will cause a surging to be seen at the other fan. Performing the fan redetection will fix this issue...


              A second recommendation would be to (at least temporarily) try replacing the fan with another one. Somefans require more power (voltage) that others to operate reliably. You problem may be that, when the system is cool and QST slows down the fan, the fan is reaching a level it cannot handle and is stalling as a result. Try a different fan, borrowed from a friend or another of your PCs, and see if this alleviates the problem...