i have the same board and have quite a lot of experience overclocking it.
go into the advanced section of the bios and set these-
ai tuning=manual
pci-e=100mhz
pci clock syncronization=33.33mhz
spread spectrum=disabled
memory voltage=depending on your ram i'd start at 2.0v
cpu vcore voltage=1.35v,is a good place to start
fsb terination voltage=1.200v
nb vcore=1.25v
sb vcore-1.5v
i always set the last 3 voltages on the lowest setting,not on auto.
next go into advanced chipset config and into north bridge config
set configure dram timing by spd to disabled.
go back into advanced menu and onto fsb frequency,you will see it starts at 266.enter a no. like 280 etc,not too high to start with and save and exit.see if it will boot windows and run stuff.you could try the science mark 2 program to test it.
if it runs ok,go back into the bios and raise the fsb frequency a little more,and test it again.
if you get to a point were it fails to post(boot up) or load windows,just turn your pc off,and back on(not a reset) and it will boot up fine,with a message saying overclocking failed and to press F1.
now just go back into advanced menu and raise the cpu vcore by ONE INCREMENT.ie- frome 1.325 to 1.350.reboot and try again.
it can be very time consuming.i will help you if i can.