MBP 15" early 2008 - logic board
I had my MBP early 2008 model overheat on me just 2 weeks ago. I had recently updated to Mavericks and was running a music program called Maschine 2.0.
Symptoms: The sleep light and superdrive would turn on, no image on the screen, no boot up chime.
I was bummed out since it had lasted me faithfully for so long. I refused to give up on it . . . .
I looked online and saw that people who had similar symptoms had concluded it was a GPU chip issue, when it overheats, it detaches from the motherboard.
The fix: A GPU reflow! Much like what people where doing with their XBOX360's back in 2006.
Note: I'm an electronics engineering tech grad, so I felt confident I could reproduce their steps, and it worked.
Materials: MX4 Thermal Paste($10), WEP 858D Reflow Station ($70), Phillips set, Torx set.
While the laptop was taken apart, I also cleaned the fans of all the dust that had accumulated (this definitely played a part in the overheating), and cleaned off all the old thermal paste and applied new paste. I have a toothbrush I bought just to clean electronic ports, etc. I used isopropyl alcohol 99% to clean off the old paste, along with cotton swabs.
I reinstalled Snow Leopard and a 90 GB SSD I had laying around.
Results: This laptop feels as fast as my Mac Pro running Mountain Lion. It runs so cool now, the fans have yet to spin up in the past 2 weeks. Snow Leopard is, quite honestly, the best OS for this laptop! If you stick with it, it will reward you.