Thanks for the fast reply. I feel better already
I can't fit another heatsink to the NB, it's an Asus M2N32 which uses heatpipe cooling for some of the components.
The thing about NB HS temps is that's all it is. The temp of the HS. How hot is the actual NB?
I see what appears to be flat tops on the NB and SB in the pics of your board I am viewing. If there are fins under the flat tops then by all means, remove the flap tops, it's a styling gimmick. I see covered fins in image number 2 at this link:
The next easiest thing to do in your case is to add a fan and direct airflow straight at the NB.
If you're serious about cooling and keeping it then it becomes neccessary to remove the entire heat pipe structure from all attachments, clean everything and apply Artic Silver 5.