Computer Won't Post

[Rich]

Windows XP SP-3
eMachine T3306 (AMD SempronT 3300+ Processor) purchased 2-2006

Please help. This is my wife's computer. I turned it off last night; all was
normal. On
the way to driving my son to his baseball game, I get a call from my wife
that her computer does not turn on when she presses the button.
When I got home, sure enough, when I press the power button I can hear an
electronic popping noise from the speakers but nothing else; power supply
did not turn on. Suspecting the power supply, I removed it & hooked it up to
my daughters much newer eMachine (just to the motherboard connectors, no
drives), pressed the power button & the power supply immediately powered up
& all system fans spun up. I figure the power supply is good.
Back to the dead computer, I reinstall the power supply, remove & reseat the
CPU & press the power button. Now the case fan & CPU fan spin for 2 seconds
& stop. Excited, I press the button again & it is back to square one:
speaker "popping". Later on, dejected & dreading the process of buying a new
computer & transitioning all the data & programs (this is my wife's nerve
center of the household), I put the heat sink assembly/fan back on to close
things up & pressed the power button again for old time's sake. Once again,
the case & CPU fans spin for 2 seconds & stop, never to start again on
repeated power button presses.
What's going on?! Is the motherboard bad or not getting information from a
bad CPU? Or is it something totally unrelated to an amateur.
Thanks in advance.
Regards,
Rich S.

 

[Paul]

Windows XP SP-3
eMachine T3306 (AMD SempronT 3300+ Processor) purchased 2-2006

Please help. This is my wife's computer. I turned it off last night; all
was normal. On
the way to driving my son to his baseball game, I get a call from my wife
that her computer does not turn on when she presses the button.
When I got home, sure enough, when I press the power button I can hear an
electronic popping noise from the speakers but nothing else; power supply
did not turn on. Suspecting the power supply, I removed it & hooked it
up to
my daughters much newer eMachine (just to the motherboard connectors, no
drives), pressed the power button & the power supply immediately powered up
& all system fans spun up. I figure the power supply is good.
Back to the dead computer, I reinstall the power supply, remove & reseat
the
CPU & press the power button. Now the case fan & CPU fan spin for 2 seconds
& stop. Excited, I press the button again & it is back to square one:
speaker "popping". Later on, dejected & dreading the process of buying a
new
computer & transitioning all the data & programs (this is my wife's nerve
center of the household), I put the heat sink assembly/fan back on to close
things up & pressed the power button again for old time's sake. Once again,
the case & CPU fans spin for 2 seconds & stop, never to start again on
repeated power button presses.
What's going on?! Is the motherboard bad or not getting information from a
bad CPU? Or is it something totally unrelated to an amateur.
Thanks in advance.
Regards,
Rich S.

There are a few reasons a computer could stop like that.

1) Bad power supply. Modern power supplies have a few internal checks,
and will shut off if there is a problem detected.

2) CPU fan pulses missing. The BIOS will do a quick check of the CPU fan
speed. If the CPU fan is not plugged in, or the pulses don't indicate
a decent speed for the fan, the BIOS can switch the computer off.

3) Modern CPUs (both Intel and modern AMD) have THERMTRIP. If the CPU
overheats, past the THERMTRIP temperature threshold, that can be
used to switch off the supply. On some computers, the plastic tab
that the CPU heatsink clamps to, snaps off, leaving the heatsink
loose.

There is one other protection feature, which is on some Vcore regulators
(motherboards have power circuitry on them too). The Vcore can have overcurrent
detection, and when triggered, the computer stays running (you can hear fans).
But in fact the CPU doesn't have power, so cannot compute. This doesn't match
your symptoms. Your symptoms would be a match for 1 through 3 above. You've
tested the PSU (but the "good" computer may present less loading than
the "bad" computer).

And when you reseated the CPU, you probably put fresh thermal interface
material on it (paste), in case the old stuff was scratched up.

The next step I'd recommend to you, is disconnect subsystems one by
one, in case something is "holding the system hostage". Sometimes
a failed drive can prevent the rest of the machine from working
right. Disconnect both the data cable and power cable from a drive
you're removing, then retest. Maybe you'll get lucky, and find it
is something other than the motherboard or PSU.

Keep careful notes, of what cables go where

Paul

 

[Ken]

Windows XP SP-3
eMachine T3306 (AMD SempronT 3300+ Processor) purchased 2-2006

Please help. This is my wife's computer. I turned it off last night; all
was normal. On
the way to driving my son to his baseball game, I get a call from my wife
that her computer does not turn on when she presses the button.
When I got home, sure enough, when I press the power button I can hear an
electronic popping noise from the speakers but nothing else; power supply
did not turn on. Suspecting the power supply, I removed it & hooked it
up to
my daughters much newer eMachine (just to the motherboard connectors, no
drives), pressed the power button & the power supply immediately powered up
& all system fans spun up. I figure the power supply is good.
Back to the dead computer, I reinstall the power supply, remove & reseat
the
CPU & press the power button. Now the case fan & CPU fan spin for 2 seconds
& stop. Excited, I press the button again & it is back to square one:
speaker "popping". Later on, dejected & dreading the process of buying a
new
computer & transitioning all the data & programs (this is my wife's nerve
center of the household), I put the heat sink assembly/fan back on to close
things up & pressed the power button again for old time's sake. Once again,
the case & CPU fans spin for 2 seconds & stop, never to start again on
repeated power button presses.
What's going on?! Is the motherboard bad or not getting information from a
bad CPU? Or is it something totally unrelated to an amateur.
Thanks in advance.
Regards,
Rich S.

I agree with Paul. If the voltages (particularly the +3.3v) fail to
come up fast enough on your MB, the PS will shut down. Placing the PS
on another MB may well work if the current required by it is slightly
less than the MB it was on originally. Often the cause of this type of
failure is a lost in capacitance for the PS capacitors.

If it were my computer I would either borrow a relatively new PS of at
least the wattage that was in your computer and try it, or buy a new
one. Odds are your problem will have been identified.

 

[Ken]

Windows XP SP-3
eMachine T3306 (AMD SempronT 3300+ Processor) purchased 2-2006

Please help. This is my wife's computer. I turned it off last night; all
was normal. On
the way to driving my son to his baseball game, I get a call from my wife
that her computer does not turn on when she presses the button.
When I got home, sure enough, when I press the power button I can hear an
electronic popping noise from the speakers but nothing else; power supply
did not turn on. Suspecting the power supply, I removed it & hooked it
up to
my daughters much newer eMachine (just to the motherboard connectors, no
drives), pressed the power button & the power supply immediately powered up
& all system fans spun up. I figure the power supply is good.
Back to the dead computer, I reinstall the power supply, remove & reseat
the
CPU & press the power button. Now the case fan & CPU fan spin for 2 seconds
& stop. Excited, I press the button again & it is back to square one:
speaker "popping". Later on, dejected & dreading the process of buying a
new
computer & transitioning all the data & programs (this is my wife's nerve
center of the household), I put the heat sink assembly/fan back on to close
things up & pressed the power button again for old time's sake. Once again,
the case & CPU fans spin for 2 seconds & stop, never to start again on
repeated power button presses.
What's going on?! Is the motherboard bad or not getting information from a
bad CPU? Or is it something totally unrelated to an amateur.
Thanks in advance.
Regards,
Rich S.

I agree with Paul. If the voltages (particularly the +3.3v) fail
to come up fast enough on your MB, the PS will shut down. Placing the
PS on another MB may well work if the current required by it is slightly
less than the MB it was on originally. Often the cause of this type of
failure is a loss in capacitance for the PS capacitors.

If it were my computer I would either borrow a relatively new PS of
at least the wattage that was in your computer and try it, or buy a new
one. Odds are your problem will have been identified.

 

[Rich]

I know you've already done it, so the warning is too late ... but don't
put a suspect power supply into a good machine because if the power supply
is bad then you risk blowing up components in your otherwise good pc. Been
there, done that, lived to regret it. Power supplies are quite rugged and
you are unlikly to damage it so its better to borrow the good power supply
from your working eMachine and put that into your older pc. It might be
worth trying even now since many of the other posts have still questioned
the power supply.

Wow, thanks for the advice. I never thought of that! I see my follow up post
never appeared....long story short: out of desperation & with no expectation
I proceeded to go through the motions of basic troubleshooting of
disconnecting all peripherals & it booted up with the old PSU. It seems to
be a USB port or hub problem, so it works fine without any USB devices
connected & sometimes won't boot if a USB device or a hub I've had is
connected. So, in this scenario, had I brought the good PSU to the dead
computer it still would have not booted & I would still have jumped to the
wrong conclusion of bad motherboard until I disconnected the USB hub.
Thanks to all who replied. I learned much.
Regards.

Rich S.