Just running the CPU at a full load. It generates more heat, helping the Arctic Silver to spread itself and get in a comfortable position. When the AC is comfortable and happy, it's more willing to transfer heat .
I'd say, get Prime95, run a Torture Test overnight, and it should be fine.
Keep in mind; Arctic Silver says that it takes 250 hours of use before the maximum cooling can be reached, so don't be discouraged by less-than-perfect temps in the first uses.