I'm pretty sure the e6300 is a conroe chip.. I have one, its based on the 65 nm tech. The multiplier on mine can be adjusted from 6 - 7. I run mine at at 400 mhz FSB with the multi at 7.. The only adjustments I make in the bios are upping the voltage given to the ram(2.2 volts) to get it to run at a 1:1 ratio (800 mhz). The chip should be left at stock as most conroe's are stable at much higher speeds than 2.8ghz.
I use the p5ld2 which is unstable above 400 mhz. If you are using a new motherboard than you might be able to get upwards of 450 mhz FSB speeds, in which case upping the voltage on your cpu and the northbridge will help.
Bottom line - Its best to leave everything at stock and up the FSB while feeding the memory adequate voltage. (at least from my experience).
Pedros