I give up!
I am fairly computer literate, having previously worked for a small company spending my days fixing PC's, but my current problem has so far escaped me;
Initially my computer started proving temperamental on a cold start up. Typically in the morning I would turn the PC on and there'd be nothing, no beeps, no POST, the fans would whirr up and the screen would sit blank. Then after a period of 10 or so minutes I could press the restart button and it would load up as usual. Once booted up I could perform warm restarts as many times as I like and it would be fine. It would just need this 5 to 10 minute period of 'warming up' from cold.
However I came home one evening, having left the PC on during the day I just sat down and started using it, I went to perform a warm restart but shock horror, it wouldn't load as before. From that point it didn't matter what I did, press the power button and it'd sit there running, but remaining completely blank. No POST, no beeps, no nothing.
I have tried swapping the PSU over, varying combinations of PCI cards in and out, variations of drives plugged in/left out and that did nothing. I felt after all that it would most probably be a motherboard fault, so I bought a new Mobo and 512Mb of DDR RAM.
I installed that this evening, pressed the power button and the PC initially loaded...success! I immediately went to the BIOS screen on first boot, changed all the settings to as required, pressed yes to the restart and save settings option, and before I knew it I was back to square 1. I press the power button and it's a black screen.
In conclusion I suspect that, by process of elimination, the fault must be with the GFX card or the CPU itself. The real puzzler is that on swapping the mobo earlier it initially loaded fine.
ASI