Clearing CMOS memory - What did I fix?

[bert8for3]

I'd sure be curious to know what it was I "fixed" last night on my pc.

I pressed the start button to boot up, and nothing happened. Then I noticed that the system was starting to whir up (fans), but only for a second or two, then going dead, and repeating this over and over.
I fiddled with the switch in case it wasn't making proper contact, tried again, same thing.

Then I noticed from the POST display on the m/b that it was showing complete power off. Some thumbing through the m/b manual and a reboot and looking at the POST display showed that the system wasn't completing the POST and was going to power off.

After sweating a bit and thumbing the manual some more, I figured that the thing to do (being the only thing I could think of) would be to clear the CMOS memory, which I did with some trepidation. Then everthing was fine. I had to reset system date/clock in bios, but no big deal.

I haven't a clue though what caused this. Any ideas?