Ok, well I have flashed to latest BIOS - No improvement. So, I thought I would try another CPU. Athlon XP 2600+ still wouldn't boot. But a 2000+ did.

3DMark 2000 is now 9584
3DMark 99 is 11474 / 27260

This is with nvidia driver 30.82

Quake 2 can t be a pain if there are some old .cfg files.
I think it can help to remove or rename them all, excepted config.cfg IIRC.