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Upgraded M/Board and PSU won't start a 2nd time

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April 5, 2010 4:46:05 PM

I've just upgraded a PC with a new motherboard and PSU.

It booted first time, ran for a couple of minutes, then shut itself down,
and is now almost, but not quite, completely dead.

What should I do now?

Details:

I had a 6 or 7 -year-old MESH PC running XP It started getting
temperamental: initially wouldn't shut down (it simply started
booting again). Then wouldn't start at all.

Replaced power supply. No difference.

So bought a new motherboard-and-CPU bundle: ECS GS7610
motherboard and Athlon 3200 processor. And 1GByte RAM.

Kit required me to fit heatsink to processor (which I did,
using a thin layer of Antec thermal stuff). Then put it into
the case. Connected up PSU, and tried
powering up without any RAM: fans spun, but
nothing else happened.

OK, fit the RAM, connect the disks, press the power button, and...

It boots! Right through to Windows XP login screen!
Smiles and celebration.

But I can't log in because I forgot to attach the keyboard or
mouse. Rats. Find them and plug them in....

About the time I'm doing that, I notice that the machine is
busy doing something on disk.

Windows Update, maybe? No, no Ethernet connection.
Hmmm.. What can it be?

The mouse and keyboard are still unresponsive, so can't
DO anything --- I'll just have to wait for it to finish....

Start rummaging to find the ethernet connector, and
notice out of corner of eye that the XP login
screen seems to have been replaced by the BIOS.
Maybe it is re-booting? But before I can look closer,
the machine powers itself off.

And now it is completely inert. The power button does
nothing at all.

With one TINY exception. The first time I press the power
button after I've turned the PSU off and on again,
the case and CPU fans to spin for about half a second.

And that's it. Otherwise, it's a brick.

Any suggestions on what to try now?

Robert.
a c 78 V Motherboard
April 5, 2010 6:19:34 PM

Please read the stickies here. Your description sounds like your CPU fan and heatsink are not properly seated with the appropriate thermal paste (e.g., Arctic Silver 5), or the CPU fan is not connected, or the CPU power lead in not connected to the board. The computer will shut-down when the CPU temp exceeds the limit set in BIOS. There could be other problems: verify that all the power leads are properly seated to the board, the HDD(s), the GPU(s), case fans, etc.

If none of the above works, then CLR_CMOS using the jumper:
-- Unplug the power cord,
-- then CLR_CMOS, by moving the jumper from pins 1 and 2 to 2and 3 for a little while,
-- then reset the jumpers to oins 1 and 2.
-- Plug in the power cord and try booting again.
April 5, 2010 7:09:03 PM

Thanks for the response, Treefrog.

I have read the stickies. There were no "spare" stand-offs;
The 4-pin CPU power lead is connected (as is the main 24 pin one);
the video is on-board; the only stick of RAM is well seated
in the right slot; the CPU came in the socket, without
a plastic guard and its fan was running; there were no loose
screws in the case; and nor did I touch anything between the
machine running, and it not starting, so static seems unlikely.
Oh, and I have tried clearing the CMOS.

Shutting down after a couple of minutes did make me think
"overheating". The heat sink was properly mounted, and
I used Antec "Reference" compound, as per their instructions.
Looking at some You Tube "how to" movies, I used a more paste
than most of them, but not a lot. And I've just taken the heatsink off:
there was just a trace of thermal compound squeezed to the
edge of the CPU in a places, but definitely none on the CPU
socket or pins.

Wouldn't an overheating CPU have shut itself down?

And would a temperature-damaged CPU give the symptoms
I'm seeing, with not even the motherboard fans starting?

Robert.




Related resources
a c 78 V Motherboard
April 5, 2010 7:33:16 PM

It could be a damaged CPU, but your update suggests it also could be a bad connection with the main power cable, the 20/24-pin cable from the PSU to the board. I had that same problem on my son's P4 board yesterday. I had disconnected the 20-pin connector to access some other cables. Fans spun about a second before shut-down. I had to remove/re-install the 20-pin cable a couple of times before the machine POSTed - it's been running fine since then.
April 9, 2010 11:09:14 AM


Thanks Treefrog: tried re-plugging the PSU, but no joy.

So I decided to take the motherboard back.

But before I did, as a last ditch sanity check, I tried
"breadboarding" one more time.

I took the PSU and motherboard out of the case, connected
them, and then used a small screwdrive to short the "Power SW"
links. And the CPU fan ran until I shorted the links again for
several seconds to shut it down!

SO.... I attached the keyboard and monitor, and tried again.
The fan started, and the screen showed the BIOS complaining
that there was no boot device (which was true --- no drives
connected).

Proof that I definitely HAVEN'T overheated the CPU, and
that the RAM works. Happy bunny!

Shut down and try again, but this time I
was fast enough to hit "DEL", and got into the BIOS.
I clicked about, looking at the hardware status, setting
the clock and so forth, for about 10 minutes. Everything
worked as normal: fan speed was reading 3800, and CPU
temperature was 78 F (about 25 C).

I tried enabling the hardware thermal shutdown, Just In Case,
saved settings and then shut down.

So I moved the board back into the case, resting it
on its stand-offs, connected the power switch and
speaker, and tried again. And we were back to
to "fans run for half a second, then brick".

So I took it back OUT of the case again.... and
it's still in "fans for half a second, then brick" mode!

So it does look there is a bad mechanical something.

Just moving the motherboard into the case (without
unplugging anything) and connecting the power and
reset switches has wedged it back in its
non-working state. The board would have flexed
slightly during this process, as would the PSU
cables and connections. But nothing more.

If the system gets upset by such minor
disturbance (think "adding a new disk drive"), I think
there is something wrong, either in the power
supply cables, or the board connectors, or....

So definitely "back to the shop"... Maybe they've got a
PSU checker...

Thanks for your help/suggestions...

Robert

a c 78 V Motherboard
April 9, 2010 1:46:59 PM

After the PSU check, try a replacement motherboard. Most don't arrive defective, but something IS wrong when your system randomly works or not, and the motherboard is the key component.
!