I've run another problem
it won't post! Nothing on the screen at all. The GPU fan spins up, the HDDs click to life and the KBM numlock etc LEDs flash once. I've got a little PC speaker plugged in and I don't get any error beeps.
I've installed the jumpers with 7x multiplier and 100.3MHz FSB. The manual only goes up to P3 550MHz as an example configuration but it says how to set various multipliers and FBSs. I've set the "keyboard boot" jumper to off, which the manual says is the default option. I've unplugged everything except the KBM, GPU, CPU and RAM. I then even unplugged all the RAM, GPU and CPU in turn to see if I could at least generate error beeps, but nothing...
I've done normal stuff like tried different sticks of RAM in different slots.
Any ideas? Considering it does not provide any beeps at all, I think it is the Motherboard or CPU (too much bad luck for it to be 3x sticks of RAM...)