I have a 4 year old Acer Aspire 7745g laptop that has been running hot for a while. It idles at around 50 C, but any games increases that to around 70-80 C. I'm using a laptop cooling stand with two fans, which helps a bit, but not as much as it used to. I finally decided to take it apart, dust off the gpu fan, and apply some thermal paste.
I took off the heatsink and found excess (as far as I know) hardened paste all over. My understanding was that the paste should be on the actual card, and not the green frame (picture below, because I doubt my explanation was very good). What should I do? Try to remove everything, or just the parts on the protruding little silver card (not sure what exactly it's called).
well, now that you've removed the heatsink from the components, you will need to completely clean off all the old thermal paste and re-apply it. Use isopropyl alcohol (rubbing alcohol) and reapply the thermal paste.
You have likely found your problem.
The purpose of thermal paste is to fill in microscopic imperfections in the faces of the cpu and the cooler.
Thermal paste is more conductive than the air which it forces out. But... too much will act as an insulator.
The pic looks like sloppy assembly to me.
Use alcohol to clean off all of the paste.
Use fresh material like arctic silver 5. Use very little, a drop will do. It should be only on the part to be cooled and not spill over.
It spreads out under time and pressure by itself.
Arctic silver has a video tutorial of the process.