Laptop Overheats & Shuts Down

I've had my laptop for about 3-4 years now. It has ran fine up until a month or two ago. I noticed when I would play games on Facebook the fan would start to fun faster, and eventually it would shut down due to overheating. Before this started I had to replace my battery. The battery I got is not the same one from HP. It works, but it is much larger and sticks out in the back of the laptop. Can that be the reason of it overheating? It only seems to overheat when I play Criminal Case or run dBpoweramp. I've tried opening up parts to see if it needed cleaned, but all that came off was clean, the part that seems to get real hot to touch I couldn't access, as the screws refuse to come out... Any suggestions?

 

When was the last time you have cleaned all the dust and lint out of the fan, and heat sink?

 

Never. I don't even know what a heat sink is. I did try taking it apart last night to clean the fan, but like I said after removing all the screws, it still would not come apart. I guess I will try to do more to get it apart tonight.

 

If you already have the keyboard out, or however you exposed the CPU/fan/heat sink, you can use a can of compressed air to blow the whole kit 'n' caboodle clean.

Just make sure you blow it out, from the inside and out the intake. You don't want to bury any dust bunnies where they don't belong...