Fan very loud and PC will not boot up

[leeross]

Hi there

I have a Dell dimension 8400 and recently upon boot up my fan on the PSU is
extreemly loud and the pc will not boot up.This is an intermitent fault and
does not happen all the time
Is this a simple fan or psu fault.

 

[Noozer]

Hi there

I have a Dell dimension 8400 and recently upon boot up my fan on the PSU
is
extreemly loud and the pc will not boot up.This is an intermitent fault
and
does not happen all the time
Is this a simple fan or psu fault.

A messed up fan won't stop the computer from booting, so I'd suspect that
the PSU overheated and is failing.

If your comfortable opening up the PSU, you should be able to swap the fan
out for around $5. Much cheaper than a PSU. More likely than not this won't
solve the booting issue.

Also, being a Dell, you have to make sure that you have a standard PSU in
there. Dell doesn't always use them, making swapping it out a pain.

 

[kony]

Hi there

I have a Dell dimension 8400 and recently upon boot up my fan on the PSU is
extreemly loud and the pc will not boot up.This is an intermitent fault and
does not happen all the time
Is this a simple fan or psu fault.

Is it possible the fan had always started up at max RPM,
only to be immediately throttled down in RPM by the
motherboard bios as the POST progresses before booting the
OS? If so, it might be that the system is halting or bios
failing to execute then precludes the throttling down of the
fan.

.... or is the PSU fan entirely controlled by the PSU, no
connection to the motherboard? Most retail systems don't
control the fan externally but on an OEM system, they can do
it if they chose to.

I would suspect a PSU fault still, and check it with a
multimeter.