You can post this at hardware---> S478 thread there.From there we are able to help you. Usually for a northwood it won't run at very high temp when on full load.60+ degree celcius is considered safe range for a northwood proc.

Such a high temperature the proc will be throttle. Like P4 it will starts giving empty instructions to cool the the proc while it's still running at the same speed. Other newer proc will use different method to cool down the proc when reach high temp.