Question : Problem: CPU Fan stops few seconds after starting PC...no display on the monitor

Hi friends !

In my PC&

1.Harddisk and CD-ROM  are attached to IDE controllers.
2.Floppy drive is connected to Floppy drive controller.
3.RAM is also present and properly fixed in RAM slot.

But when I power on the PC, there is no beep sound. CPU Fan starts and then stops just after a few seconds. (THERE IS NO DISPLAY ON THE SCREEN)  (Because fan rotates for few seconds, I reached on the conclusion that there is no supply problem to fan and also for the motherboard.)

 (MONITOR IS OK, IT IS WORKING WITH OTHER MACHINE)

One by one, I removed signal cables from Harddisk, CD-ROM, Floppy drive and I removed NIC card from PCI slot, Video card also (That connects Monitor to motherboard). But the problem is still there.

BUT WHEN I REMOVED THE RAM, THE FAN WAS ROTATING CONTINUOUSLY.

IS THERE INSUFFICIANT SUPPLY PROBLEM TO MOTHERBOARD ? Has anyone faced the same problem ? Why the cpu fan stops just after few seconds ?

Your help is highly significant&

Hemant

Answer : Problem: CPU Fan stops few seconds after starting PC...no display on the monitor

When the mobo starts to work, by default, before the POST, it powers the CPU fan for safety purpose. After the start sequence of POST, then the CPU fan is controlled by the ACPI of the mobo. Is something went wrong, then the ACPI didn't start up, so the CPU fan stops (maybe some signals inside the motherboard are in suspended mode, before ACPI takes control of them). If you remove the RAM, then the POST don't have a chance to start, then the CPU keep running (as i explained before, this is the default operation).

This is a sympthom that something is going badly. This happened once to me, when I tried to drive a CPU that required more power than it could be supplied from the motherboard. After replacing the CPU with a good one, then it worked fine.

Before doing anything, i recomend you to set the cmos values to default (maybe the bus clock was set up too much high), this is often done by setting a pin configuration, or you may remove the cmos battery for a while.