He is saying you are going to want to overclock the CPU. Sandy bridge chips will do 4ghz on stock cooling easy. so there is no point not to overclock it to that.
This machine will be on for a good 14 hours a day, sometimes 24 hours a day for several days in a row probably. I won't bother OC'ing it to start with. I can always change my mind, it doesn't cost anything extra to OC it does it? Isn't it just a case of changing a jumper/connector to choose a different multiplier? I know I will want to do it, just not for the first year or so. I want that as a bonus half-upgrade half way through the computers life. I'm already going to be shocked at the stock performance after being laptop-powered for the last 3 years.