help! p4b533 sb_pwr blinking but mobo dead

[joeprogrammer]

Hi all,

I replaced the heatsink on my mobo and obiously broke either the cpu or
the mobo... Does a blinking sb_pwr mean one or the other... or both?!?!

I plug-in, flip the psu switch and the sb_pwr starts to blink. I push
the power button but the mobo remains inactive (other than the blinking
sb_pwr led). If I safely remove the cpu and try reapplying power same
thing happens - does this mean the cpu is broke, the mobo is broke...
or perhaps the psu (3 yr old zm300a)?

I can't find any asus docs on a blinking sb_pwr led. And info
appreciated.

cheers

 

[Paul]

Hi all,

I replaced the heatsink on my mobo and obiously broke either the cpu or
the mobo... Does a blinking sb_pwr mean one or the other... or both?!?!

I plug-in, flip the psu switch and the sb_pwr starts to blink. I push
the power button but the mobo remains inactive (other than the blinking
sb_pwr led). If I safely remove the cpu and try reapplying power same
thing happens - does this mean the cpu is broke, the mobo is broke...
or perhaps the psu (3 yr old zm300a)?

I can't find any asus docs on a blinking sb_pwr led. And info
appreciated.

cheers

Are you referring to the green LED on the surface of the
motherboard ? It is wired directly to +5VSB, and if the
LED is flashing, that means the PSU +5VSB supply is being
overloaded. When the green LED on the motherboard is on,
it should be lit nice and steady. If the LED blinks, then
each time the LED goes out, the PSU secondary output circuits
will shut off at the same time. The +12, +5, +3.3V etc. on the
output of the PSU, rely on a steady level on +5VSB to work.
So, if the green LED on the surface of the motherboard
won't stay on, neither can the rest of the ATX PSU.

A typical reason for this happening, is a bad PSU.

A less typical reason, is some wiring error you've made,
or an accidental short of an extra standoff underneath the
motherboard. Since you only changed the heatsink, it is
less likely to be a wiring error, unless you removed and
replaced some wiring while working on the board.

With the high frequency of power supply failures, I'd
swap in a spare PSU and see what happens. That would be
my first test.

HTH,
Paul

 

[joeprogrammer]

Thanks for the suggestion Paul. I think I'll track down a PSU and try a
swap.

Funny thing - I removed all cabling from the mobo then started wiring
things up one at a time and lo and behold it booted. Leave it for a day
though and it has acted up again. I wonder if that is how PSUs behave
before they finally give up the ghost. I'll keep you posted.

cheers