ASUS P4P800 problem! system halted

Well, I have a very mysterious situation here... I hope someone could help me.

here it goes:

I recently got hold of a asus p4p800 motherboard, it worked fine and everything. until I changed some settings on the bios. (performance for cpu and memory, I can give the specific things I changed if needed).

after the change it boot up and everything seemed to start, BUT the monitor´s light didn´t change (yellow to green) like if the computer was turned off or there was no video card. then if I try to turn off the machine, it doesn´t, the cpu fan is working, the HDs are working but the machine can only be turned off if I turn off the no break itself. it´s like it is halted and the monitor is black and didn´t initialize as said above.

well, first thing I tried was to clear the CMOS, well I followed the instructions and it doesn´t work (maybe the instructions are wrong on the manual? can someone tell me exactly how to do it?)

but it gets interesting, well I´m trying to clear the CMOS again and then I turn it on and suddenly IT WORKS! it´s like back to normal again... BUT then I notice that everytime I turn on the computer it says "new cpu detected, press f1 to...".

well then I check the jumper I used to clear the CMOS and I notice that I had put it ONLY over pin 1 (instead of pin 1 and pin 2, to clear the CMOS it involves changing a jumper to position 1 2 to position 2 3 and then putting it back to 1 2), then if I put it how it should be, it goes back to what happened before.

so the only reason I was able to make it work was to put that jumper over pin 1 only, what makes the bios detect a new cpu every single time.

well I hope there are some gurus here who could help me.

ps: ask me and I´ll give more info if something wasn´t clear.

thanks in advance