depends on the case the airflow in the case and if he over clocking the pc. it depend where the chipset is on the motherboard..the type of video card that go in..if the video dumps the air outside the case or straight down onto the mb.
if it a mini case how good is the airflow and how many fans are in the case. if he picks up a gaming case that has a larger grill on top and a push-pull fans..then the chipset should stay cool even with a large video card. people with the chipset getting hot and locking up the pc would be in a small case and sli or cross fire and the video cards dump back into the pc.
If the north bridge needs to be cooled then the manufacurer sells the mobo with a heatsync already on it. I don't think I have ever seen a mobo with a fan on the north bridge heatsync, but if you did choose to add one it definately wouldn't hurt!