A7N8X Starts then Stops Immediately

[Kappy]

Problem: Newly installed motherboard. Never used. I push power button,
system starts to run for 2 to 5 seconds, then shuts down. Everytime.

This is an upgrade to an A7N8X with Athlon XP2800+ cpu and it has not
yet worked. I believe that I have installed everything correctly. The
memory is brand new KBYTE 512 2700. I have swapped power supplies and
memory with another computer. I have tried booting without the hard
drive attached, without the video card installed and with all other
cards installed and removed. I even swapped power switches. The video
card is a 2001 model year card by Vision Tek. I don't know the voltage,
but the red light on the motherboard is not lighting up to indicate a
problem. The power supply is rated at 250w.

I have not yet tried removing the cmos battery.

What could be causing this?

Thanks,

Robert

 

[Blaedmon]

Could be the motherboard shorting on the case - something as simple as that,
but it sounds vague also. You could, for the benefit of elimination, try
removing the board and powering it up flat on a table, etc.

 

[Paul]

Problem: Newly installed motherboard. Never used. I push power button,
system starts to run for 2 to 5 seconds, then shuts down. Everytime.

This is an upgrade to an A7N8X with Athlon XP2800+ cpu and it has not
yet worked. I believe that I have installed everything correctly. The
memory is brand new KBYTE 512 2700. I have swapped power supplies and
memory with another computer. I have tried booting without the hard
drive attached, without the video card installed and with all other
cards installed and removed. I even swapped power switches. The video
card is a 2001 model year card by Vision Tek. I don't know the voltage,
but the red light on the motherboard is not lighting up to indicate a
problem. The power supply is rated at 250w.

I have not yet tried removing the cmos battery.

What could be causing this?

Thanks,

Robert

Overheat or BIOS isn't detecting tachometer pulses on the
CPU fan ? The heatsink contact patch should be centered over
the CPU (a 180 degree rotation of the heatsink might not give
the right result). There should be a thermal pad or thermal
paste (not just a dry heatsink) to enhance contact between the
CPU and the heatsink. The CPU fan should have three wires, one of
which is the tachometer wire. The CPU fan should spin at least
1800 RPM, because otherwise the BIOS can read such a fan as
zero RPM.

If it still isn't working, move the CPU fan cable to one of the
other fan headers.

HTH,
Paul

 

[Scotter]

I had same exact problem with same MB.
I ended up replacing every part until I thought maybe it had something to do
with the wall socket.
I ran a 3-prong extension cord from a different socket as far on the other
side of the house as possible and voila! The machine works fine!
I need to remember to get an electrician out to test the bedroom socket,
which is the one I was using initially.

 

[Apollo]

Problem: Newly installed motherboard. Never used. I push power
button, system starts to run for 2 to 5 seconds, then shuts down.
Everytime.

This is an upgrade to an A7N8X with Athlon XP2800+ cpu and it has not
yet worked. I believe that I have installed everything correctly.
The memory is brand new KBYTE 512 2700. I have swapped power
supplies and memory with another computer. I have tried booting
without the hard drive attached, without the video card installed and
with all other cards installed and removed. I even swapped power
switches. The video card is a 2001 model year card by Vision Tek. I
don't know the voltage, but the red light on the motherboard is not
lighting up to indicate a problem. The power supply is rated at 250w.

I have not yet tried removing the cmos battery.

Your psu isn't up to the job, get 300w minimum, by that I mean a good
quality branded psu.

 

[rstlne]

Problem: Newly installed motherboard. Never used. I push power button,
system starts to run for 2 to 5 seconds, then shuts down. Everytime.

This is an upgrade to an A7N8X with Athlon XP2800+ cpu and it has not
yet worked. I believe that I have installed everything correctly. The
memory is brand new KBYTE 512 2700. I have swapped power supplies and
memory with another computer. I have tried booting without the hard
drive attached, without the video card installed and with all other
cards installed and removed. I even swapped power switches. The video
card is a 2001 model year card by Vision Tek. I don't know the voltage,
but the red light on the motherboard is not lighting up to indicate a
problem. The power supply is rated at 250w.

I have not yet tried removing the cmos battery.

What could be causing this?

Thanks,

Robert

Do what BladeMon says first..
Is this your first ever computer that you have built..
did you add a Heatsink and Fan unit on top of the processor (yea, I take
everyone as one so dont get pissy)

Once you get it on the table as blademon says then look and make sure that
the heatsink is sitting on the cpu correctly.

Also after it shuts off (if the fans on the heatsink were spinning) then
touch them, see if they are warm.. try near the top of the fan

It SURE SURE SURE sounds to me like thermal protection (fan speed protection
should be off by default)

 

[Kappy]

It was Thermal Protection. I switched the heat sink around 180 degrees
and it started right up. Thank you very much for your insight and help