Since that is not an FX cpu, your only choice for overclocking is to raise the FSB. Most ASUS boards will let you raise just the CPU FSB, and let you have the memory out of sync. I don't suggest this, as it can lead to some performance issues, but overall you don't have much headroom. That older core CPU, without getting exotic, you probably won't be able to get 10-15% above stock, and IMO will not be worth it.