Anyone with a Core i7 920 should overclock it. Most all of the 920's can hit 4GHz stable at least, especially the ones sold nowadays. Will need good heatsink/fans/TIM (NH-D14 or Megahalems are examples for heatsink, 2 Zalman ZM-F3 fans are great, and Arctic Cooling MX-3 TIM is awesome). Also will need an overclock capable motherboard.
That's a 50% speed boost from the stock 2.66GHz.
That's a 50% speed boost from the stock 2.66GHz.