Most likely cause of failure to POST?

[Graham]

Last PC I built 2+ years ago has been rock-solid. No signs of impending
doom, but today it will not boot.
Mobo LED comes on, fans spin up, the HDD light is on but stays on and no HDD
activity. No BIOS beep.

Have tried removing everything, swapping HDD, video card, and memory.
Only bit I can't swap is CPU as don't have any lying around.
Just curious if anyone else has experienced this? It's the 2nd time for
me - the first was after a lighting storm in the area - same symptoms and a
mobo swap got it working again. But there has been no lightning today...

 

[Michael Hawes]

Last PC I built 2+ years ago has been rock-solid. No signs of impending
doom, but today it will not boot.
Mobo LED comes on, fans spin up, the HDD light is on but stays on and no
HDD
activity. No BIOS beep.

Have tried removing everything, swapping HDD, video card, and memory.
Only bit I can't swap is CPU as don't have any lying around.
Just curious if anyone else has experienced this? It's the 2nd time for
me - the first was after a lighting storm in the area - same symptoms and
a
mobo swap got it working again. But there has been no lightning today...

Have you tried a known good PSU?
Mike.

 

[H. Seldon]

Graham presented the following explanation :

Last PC I built 2+ years ago has been rock-solid. No signs of impending
doom, but today it will not boot.
Mobo LED comes on, fans spin up, the HDD light is on but stays on and no HDD
activity. No BIOS beep.

Have tried removing everything, swapping HDD, video card, and memory.
Only bit I can't swap is CPU as don't have any lying around.
Just curious if anyone else has experienced this? It's the 2nd time for
me - the first was after a lighting storm in the area - same symptoms and a
mobo swap got it working again. But there has been no lightning today...

If I were you I would at least check the 5 and 12 volt rails to see if
the power supply is working at all. It seems as though it may not be.

 

[Graham]

Have you tried a known good PSU?
Mike.

No not yet I didn't think it a likely culprit - will try one tomorrow.
Cheers

 

[Squigmont]

No not yet I didn't think it a likely culprit - will try one tomorrow.

That's very likely the culprit. Fortunately, it's an easy fix. If it were
me, I'd make sure that it was a good (brand-name) power supply (Antec,
Enermax, Thermaltake, PC Power & Cooling, etc.).

 

[Sean Cousins]

That's very likely the culprit. Fortunately, it's an easy fix. If it were
me, I'd make sure that it was a good (brand-name) power supply (Antec,
Enermax, Thermaltake, PC Power & Cooling, etc.).

Here's a good sticky post about PSU's.
http://www.hardforum.com/showthread.php?t=1000883

 

[GTS]

Last PC I built 2+ years ago has been rock-solid. No signs of
impending

That's very likely the culprit. Fortunately, it's an easy fix. If it were
me, I'd make sure that it was a good (brand-name) power supply (Antec,
Enermax, Thermaltake, PC Power & Cooling, etc.).

OK I tried two new PSU's - no go.
However something very strange that I have not heard of before - I can start
the PC by blowing on it!
No Really - last night having tried to get it running umpteen times and
running out of ideas, I was feeling pretty deflated and must have let out a
big sigh / puff of air and I suddenly I got the elusive POST beep, and it
proceeded to boot into the OS as if nothing had happened. I put it down to
coincidence.
I added back all my cards and drives, rebooting after each addition - all OK
Then this morning back to square one - it would not POST. All fans on, power
and HDD lights on, but no beep / boot. Nothing ventured nothing gained I
just took of the side panel, took a big breath, and blew onto the
motherboard - and again it has started and I am using the PC to send this
post.
So now I have a real mystery - what could be preventing the POST that is
cured by me blowing the PC?
Any suggestions much appreciated
Graham

 

[GTS]

Last PC I built 2+ years ago has been rock-solid. No signs of impending
doom, but today it will not boot.
Mobo LED comes on, fans spin up, the HDD light is on but stays on and no HDD
activity. No BIOS beep.

Have tried removing everything, swapping HDD, video card, and memory.
Only bit I can't swap is CPU as don't have any lying around.
Just curious if anyone else has experienced this? It's the 2nd time for
me - the first was after a lighting storm in the area - same symptoms and a
mobo swap got it working again. But there has been no lightning today...

UPDATE
OK I tried two new PSU's - no go.
However something very strange that I have not heard of before - I can start
the PC by blowing on it!
No Really - last night having tried to get it running umpteen times and
running out of ideas, I was feeling pretty deflated and must have let out a
big sigh / puff of air and I suddenly I got the elusive POST beep, and it
proceeded to boot into the OS as if nothing had happened. I put it down to
coincidence.
I added back all my cards and drives, rebooting after each addition - all OK
Then this morning back to square one - it would not POST. All fans on, power
and HDD lights on, but no beep / boot. Nothing ventured nothing gained I
just took of the side panel, took a big breath, and blew onto the
motherboard - and again it has started and I am using the PC to send this
post.
So now I have a real mystery - what could be preventing the POST that is
cured by me blowing the PC?
Any suggestions much appreciated
Graham

 

[justindavid]

UPDATE
OK I tried two new PSU's - no go.
However something very strange that I have not heard of before - I can start
the PC by blowing on it!
No Really - last night having tried to get it running umpteen times and
running out of ideas, I was feeling pretty deflated and must have let out a
big sigh / puff of air and I suddenly I got the elusive POST beep, and it
proceeded to boot into the OS as if nothing had happened. I put it down to
coincidence.
I added back all my cards and drives, rebooting after each addition - all OK
Then this morning back to square one - it would not POST. All fans on, power
and HDD lights on, but no beep / boot. Nothing ventured nothing gained I
just took of the side panel, took a big breath, and blew onto the
motherboard - and again it has started and I am using the PC to send this
post.
So now I have a real mystery - what could be preventing the POST that is
cured by me blowing the PC?
Any suggestions much appreciated
Graham

I'm guessing your breath is cooling something that could be initially
overheating when the machine boots up? Or your breath is getting a
fan moving that otherwise would not be moving without assistance?

 

[GTS]

I'm guessing your breath is cooling something that could be initially
overheating when the machine boots up? Or your breath is getting a
fan moving that otherwise would not be moving without assistance?

Well all the fans are spinning fine, and once I get the PC going the BIOS
health information, plus Sandra and Everest in Windows, show nice low CPU
HDD anf GPU temps - I have not had any heat problems with this build.
I have used the blowing technique to boot the PC over a dozen times now -
trial and error has shown that the area best blown on is the bit between the
CPU socket and the PS2 sockets. It is a Biostar M71F mobo and I am not sure
what, in that area, can cause this behaviour. I plan to remove the mobo and
give it a good blow with compressed air as there is a lot of dust accumalted
in that area....
Graham