Like DJ said, if those temps are load temps, they are very good. You may have won the CPU lottery and received aQ6600 with an unusually low VID.
Depending on your CPU VID, you will reach the thermal limits of an ACF7P at around 3.2 - 3.3 GHz. I know. That's the first after market cooler I bought.
If the CPU chip can go to 3.6 GHz, you will need something like a TRUE or Xig Dark Knight.
If your memory settings are on Auto, you are quite likely limiting your overclock. Go into the BIOS and change the System Memory Clock from Auto to 2.00.