So, I replaced the CPU, and finally got everything working. Was fine, stable, and I was happy. But then I had to fudge with the Overclocking controls of the mobo, and I did the following:
CPU voltage control: 1.35v
NB/HT-link voltage: +0.1v
FSB-Memory clock mode: Unlinked
CPU host frequency: 333mhz
Memory frequency: 800mhz
CPU Multiplier: 9x
And from that point on - black screen. No beeps, nothing. CMOS clearning didn't help. Replacing a battery - didn't help. Disconnected the video, the HDs/DVDs, took out the CPU and memory - still no beeps. So - just the motherboard is connected now, with just the case pins and the PSU, nothing more. No beeps.
I highly doubt it has to do with the PSU, but I can check it with another PSU, just in case.
I was wondering - do you have any suggestion as to what I can do? What can it be? Any help would be appreciated, as I am truly clueless as to what to do next.
How long did you leave the CMOS out? I have read before that if things really go to hell you have to leave it out for a bit. Also, to POST you must have a CPU and RAM, and possibly a fan plugged into the CPU_FAN header.