No problems, what are your temperatures? I've found that the Prime95 Torture Test, brings out the best out of a full load temperature.
Northwood should be hovering around the lower 40's at full load at stock, they put out as much heat as AMD when your overclocking, and adding the extra voltage to it, so it goes up to 50 load. This is based on the Intel retail cooler, as many people here overclock with that.
Yodusm