Problem with Abit KT7A motherboard...

I have an Abit KT7A motherboard, with an 800mhz Duron clocked to 1000mhz. When I put it all together and first turned the system on, everything went fine. But after a few bios changes and reboots, the system started going off after a few seconds of being switched on, making a fast ticking noise from the system speaker. Clearing the cmos and rebooting didn't help. It just displays the bios info for a few seconds, the display goes off and the ticking noise starts.

I thought maybe it was a power problem, so I disconnected the hard disk and dvd drive from the PSU, but still the same problem occurs. I even tried disconnecting the keyboard, but no change.

Any ideas what it could be?

Well you probably don't want to here this but I would suggest taking everything out except the components need to run the PC (mobo,cpu,vid card,so on) and then boot up. Put them back in one at a time and see which component causes the noise. If it's with just the core components then you will have to start replacing them one at a time. Try to borrow someones CPU or mobo. Good luck.