At this point I would remove all non-essential stuff and see if I can get it to come up. IDE cables, floppy cables, basically everything except: Vid card, RAM and CPU. Also clear CMOS once again.
If it still won't POST, the next step would be to try sawpping the 3 items I mentioned above. Probably not do-able unless you've got a computer shop in your basement (like I do :wink: ).
<i>It's always the one thing you never suspected.</i>