Not familiar with that motherboard, sounds suspicously oem.. But really with a locked cpu you would have to use the reference clock for overclcoking. This generally means overclocking the ram as well, so an unlocked multiplier is the preferred method.
Here's an article to look at:http://www.tomshardware.com/reviews/amd-cpu-overclock,2396.html
Its a bit out of date as far as the AMD overdrive is concerned, but still worth a read.