Cheers Richard,
I had a squizz on the power suply. It's a Suntek model no. AM608B1-300WS. It has an AMD approved and Intel +12V sticker on it.
Voltage. 115Vac/230Vac.
Output. +12 -12V
16A 0.8A
Current. 6.3A/5A
-5v +5Vsb
0.5A 2A
Freq 47Hz~63Hz
+5V +3.3V
30A 22A (combined 180W)
Great tip regarding the diagnostic LED's. I have forgotten about them.
Any way, fired it up (minus the HD, FD, DVD and burner). I get a message on the monitor, "boot failure". Oooh goody, reattach the HD and FD. Restart. Back to the original fault. I peer at the LED's and I watch what was going on. On the first effort it goes all the way through the sequence and then goes back to the 3rd LED symbol. ie the "memory detection test". It says it will hang if the memory module is damaged or not installed properly. Bugga!!
I reseat the memory. Same result (although it just stops at the 3rd check. It doesn't go any further). I try all positions with the same result. It hangs at the memory check.
As far as I am aware I haven't had a power spike or any thing like that. Perhaps it just decided to fail. This computer has run previously as configured as above with the power supply. (Admittedly, it was still a bit buggy but I was working my way through them)