Maybe thermal paste between CPU and heat sink has dried out? If so, you will need to disasseble your notebook, carefully remove heatsink reaply new thermal paste, and assemble your computer. See my reply here

LG R500 Notebook crashing

BTW: get service manual before disassembly - you can probably google it.

Maybe thermal paste between CPU and heat sink has dried out? If so, you will need to disasseble your notebook, carefully remove heatsink reaply new thermal paste, and assemble your computer. See my reply here

LG R500 Notebook crashing

BTW: get service manual before disassembly - you can probably google it.