LukeD wrote:
Not a single logic board replacement had fixed it.
Logic boards should only be replaced for extreme circumstances.
LukeD,
Hate to correct you, but the 3rd replacement of my MB 5,1's (Original late 2008 model, currently running 10.6.8) logic board actually seemed to fix the flickering issue. For me, the issue started after I upgraded to Snow Leopard. I originally assumed it was software based, but I believe there were people still running Leopard who also experienced the problem.
I eventually had it serviced (replaced logic board), then again after it started flickering after a few days (again replaced logic board, and the display), and then a third time after a few days (again, the logic board was replaced). The last replacement was performed in May, 2011. My AppleCare warranty expired in Oct, 2011. Since the last logic board replacement, I have not once experienced the flickering. I am VERY disappointed about this, to be honest. I was really hoping to get a replacement MB Pro when it started again after the 3rd repair. But, it never started flickering again! I'm both happy that it's been working properly, but still disappointed, as I believe that anyone who's had to have a very expensive laptop serviced 3 times for the same problem should be given a new one, even if it doesn't happen again. That would just be good customer treatment on Apple's part, and would really ensure loyalty from a lot of people who have considered leaving for other shores based on how they've seen the customer base treated.
Sorry for the long winded explanation. I've been sitting on this story and should've written about my experience a while ago. I also applied the EFI update, but was hesitant to since I wasn't sure it wouldn't reintroduce the problem again!
But, so far, so good. The update applied cleanly. Of course, I had that mini heart attack when it made the loud startup sound, but all was well after a few minutes. So far, no flickering.