So far I have - updated nForce4 chipset drivers - updated BIOS to 1805 (the latest) - updated NVidia graphics drivers - tried to POST with only CPU attached - tried to POST with 1 memory stick - tried to POST with 4 memory sticks - replaced the CMOS battery with a new one - taken a look as whether there is an obvious short in the battery case somewhere - reseated all the components and placed on a breadboard - tried a different PSU (the one i'm using is brand new anyway, and has been used in a different PC a few times)
All result in the same behaviour - in order to POST I have to power off, reset the CMOS by moving the jumper back and forth, and power back on. Anything other than this - will not POST.
I have a new build of Windows XP on this machine now (just built with resetting the CMOS each time to POST), seems to be fine otherwise.
I think the motherboard is shot to be honest, this is my last-ditch attempt before replacing the MB which seems otherwise ok.
Any help appreciated - thank you.
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I would check craigslist for a replacement board. My local craigslist has 2 DFI nforce4 boards for $30 each.