Right guys progress report
On Christmas eve I got playing with the system and took the motherboard out of the case. Put the motherboard on the cardboard box it came in with just the memory and VGA card. Shorted the power jumpers and it POSTED fine.
Put back in the case and no POST.
Looked at the area where the motherboard sits and nothing would be touching/fouling the motherboard etc. Swapped out the brass motherboard feet and screws for some spare ones I had. Replaced the motherboard and it POSTED fine.
Done several reboots, power off etc and still fine. Left running for an hour or so and still fine.
After all the Christmas palava, I managed to have a few spare hours with it again last night....
Started fine, inserted my Windows XP CD, done a full and proper format on the 500Gb SATA C:\, installed Windows XP. Again, done a full proper format on the other 500Gb SATA D:\. Installed .net Framework 1,2 & 3. Installed all the drivers including LAN, Chipset, VGA. The system had been fine all through this which was about 3 hours of runninng when I had more problems. It was absolutley flying !
The PC on the next reboot would not start up. I had no display but I had 4 long beeps from the BIOS. If I restarted the system that is all I got.
Googled up the 4 bios beeps and it was suggested either memory or VGA issues. I replaced the memory and VGA card with the spare I had from the other day and now I get no POST & no beeps. It's gone back to doing what it was the other day. Put the original VGA card and memory back in but still nothing.
I can't understand how it worked fine for 3 hours with no problems and then all of a sudden nothing.
This is doing my head in !