>>289741Unfortunately you need to take the motherboard out. Fortunately, it's really well laid out in there, so it's less effort than taking some laptops' keyboards off.
The northbridge uses a thermal pad, and you need to either keep it or replace it like-for-like. The CPU is fine with any thermal compound because of the spring-clips. Usual warnings about Arctic Silver being conductive apply; I've always preferred MX-5.
Before you do all that though, try taking the keyboard off, sticking a screwdriver in the fan to immobilise it, and blowing really hard into the exhaust on the side to clean the radiator. Your problem is way more likely to be a clogged radiator than it is to be thermal compound. If you do have the heatsink off, make sure and detach the fan and clean the fan and radiator properly.
