Faulty CPU fan cause mobo to not power up?

[BertieBigBollox]

OK. So if the mobo detects a CPU fan fails it powers off the
system....

Would a faulty CPU fan mean that a mobo wont even power up or will it
try and start everything first and then power off ?

 

[JAD]

OK. So if the mobo detects a CPU fan fails it powers off the
system....

Would a faulty CPU fan mean that a mobo wont even power up or will it
try and start everything first and then power off ?

Most will attempt to turn the fans for a split second, then shut down

 

[BertieBigBollox]

Most will attempt to turn the fans for a split second, then shut down

Not a peep from any fans....

 

[Frank McCoy]

In alt.comp.hardware.pc-homebuilt "(e-mail address removed)"

Not a peep from any fans....

If it doesn't find the fan connected, it won't try.
OTOH, the way it finds the fan *is* connected, is by sending power and
seeing if the speed-counter is detected.

So, if the other fans don't spin, it's likely something else wrong.
Bad PSU or a short will do that.
Without hitting the power-switch, do any LEDs at all light up on the
motherboard?

Try removing *everything* except for the CPU from the board, and
mounting it on a non-conducting surface when powering up. See if that
gets fans to spin for a second before the system decides "No Memory".

Then, if that works, try adding memory, then video-board, etc., one at a
time.

If it don't, try a new PSU.

 

[Pennywise]

If it doesn't find the fan connected, it won't try.
OTOH, the way it finds the fan *is* connected, is by sending power and
seeing if the speed-counter is detected.

News to me, learned something new today.

You can view the RPM of the fans and TEMPs of various areas with
Everest http://www.majorgeeks.com/download4181.html

 

[BertieBigBollox]

In alt.comp.hardware.pc-homebuilt "(e-mail address removed)"


If it doesn't find the fan connected, it won't try.
OTOH, the way it finds the fan *is* connected, is by sending power and
seeing if the speed-counter is detected.

Confused now? So if there is no processor fan connected it will try to
start?

So, if the other fans don't spin, it's likely something else wrong.
Bad PSU or a short will do that.
Without hitting the power-switch, do any LEDs at all light up on the
motherboard?

LED on the mobo.

Try removing *everything* except for the CPU from the board, and
mounting it on a non-conducting surface when powering up. See if that
gets fans to spin for a second before the system decides "No Memory".

No fans at all....

If it don't, try a new PSU.

Same with new PSU.

 

[Paul]

LED on the mobo.

There are some power supplies, that when they blow, they take
out the motherboard. There is one guy who visits these groups
occasionally, who refurbishes old computers, and I think he
can suggest a few of the "fatal" brands of power supplies. I
don't know all of them off hand. A lot of modern power supplies
behave reasonably when they fail, and don't put a transient
into the motherboard. There are some older ones, that do.

Paul

 

[Frank McCoy]

In alt.comp.hardware.pc-homebuilt "(e-mail address removed)"

Confused now? So if there is no processor fan connected it will try to
start?


LED on the mobo.


No fans at all....



Same with new PSU.

Try removing and replacing the CPU; making sure no bent or broken pins
or other similar problems.

If it still don't work; then likely you have a fried motherboard.

 

[JAD]

Confused now? So if there is no processor fan connected it will try to
start?


LED on the mobo.


No fans at all....



Same with new PSU.

down to the CPU or MB, reseat the CPU as the last resort. have you RESET the CMOS,
grasping at straws,,,,,,,,,,,,,,,,,,,,CMOS battery is good?

 

[BertieBigBollox]

There are some power supplies, that when they blow, they take
out the motherboard. There is one guy who visits these groups
occasionally, who refurbishes old computers, and I think he
can suggest a few of the "fatal" brands of power supplies. I
don't know all of them off hand. A lot of modern power supplies
behave reasonably when they fail, and don't put a transient
into the motherboard. There are some older ones, that do.

Paul

Funny you should mention that. Apparently there is a bit of a problem
with E-machines where a certain type of PSU blows and fries the mobo,
and guess which one I've got !!!!

 

[BertieBigBollox]

down to the CPU or MB, reseat the CPU as the last resort. have you RESET the CMOS,
grasping at straws,,,,,,,,,,,,,,,,,,,,CMOS battery is good?- Hide quoted text -

- Show quoted text -

Yep. Reset CMOS etc.

 

[BertieBigBollox]

down to the CPU or MB, reseat the CPU as the last resort. have you RESET the CMOS,
grasping at straws,,,,,,,,,,,,,,,,,,,,CMOS battery is good?- Hide quoted text -

- Show quoted text -

Incidentally, shouklf the mobo power up etc without a CPU, memory etc
attached?

 

[JAD]

Incidentally, shouklf the mobo power up etc without a CPU, memory etc
attached?

It will power up and 'Beep' like mad.

 

[Pennywise]

Incidentally, shouklf the mobo power up etc without a CPU, memory etc
attached?

No, the power good signal is controlled by the processor timer chip,
the Power supply would never start for more than a second.
http://en.wikipedia.org/wiki/Power_Good_Signal

 

[geoff]

On my A8V, if the fan was too slow, which it was sometimes because Zalman
has a separate fan control knob and I forget to turn it up on re-boot, the
bios will report a cpu fan error then say push one of the 'F' keys to
continue.

Not sure about no spinning at all.

-g