You need to learn more about overclocking.
I will go over the basics.
There is your CPU multiplier
Your CPU speed = FSB x CPU multiplier
Your memory speed = FSB x Memory multiplier
So you have to overclock them both at the same time.
You can however set your memory multiplier lower so you avoid overclocking your memory because memory doesn't overclock good.
Your CPU should be 2.6ghz right? The multiplier should be 13 and the FSB should be 200.
If you set your memory multiplier at 3.33, CPU multiplier to 13, and FSB to 240.
You would be your 800mhz memory clock and a 3120mhz core clock.