Turn on your PC and keep pressing the DEL key. It'll bring you to the BIOs which looks like this
From there, go into MB Intelligent Tweaker at the bottom left. In here, you will find this
Like said above, change PCI-E Frquency from Auto to 100 MHz, CPU Host Clock Control: Disable to Enable. The Multipler should be the first one there but the guy who shot the picture scrolled down. E6600 should have 9 multiper .
Raise the CPU Host frquency to make your CPU run at higher clocks. At the bottom of that page are voltages. Make sure CPU voltage is manually set. 1.35 volts is default. It is possible to run lower volts and higher clocks.
The reason why you will not be able to see the RAM clocks on yours is because you have to press CTRL + F1 before you enter MB Intelligent Tweaker.
Since I have yet to tell you about C1E, your clocks will be reduced when you're idle and will load back up to its max clock when you load something. If you want to disable this, go into Advance BIOs features and disable the option called (C1E).
EDIT********: If you look at the second picture, at the very bottom you will see PCI-E OverVoltage control. Under that, if I can clearly remember, is the CPU voltage, which in other terms is called vcore. Remember, 1.35 is default. It is possible to run at 3.0GHz with 1.28 vcore.
Please check your temps and tell us what both of these program says.