it helps if you post the problem, we are here to help but please but in a best effort basis to make that task as simple as possible
Now seeing as that board has an ami bios (per the asus site) i am going to assume that "Mega-tron BIOS" is some form of win app you are running. Which would lead to a 4gig cap if you have a 32bit os. win apps for setting bios and/or overclocking are a horrible idea by the way.
hope that helps if not clearly state problem with details