ANTenna Blog -- Apple

The heart of a modern personal computer consists of two powerful microprocessors — the central processing unit and the graphics processing unit. Problems with either of these critical components can lead to frustration, or worse, for users. Sadly, problems with the GPU seems to be common among users of some older Apple MacBook Pro notebooks.

In my personal MacBook Pro — which hasn't experienced any problems so far — the GPU is an Intel Core 2 Duo processor. The GPU is an Nvidia GeForce 8600M GT chip with 256MB video RAM. That GPU seems to be causing some real issues, due to a manufacturing defect.

As you can see from this discussion thread on Apple's site, some users are experiencing blank screens both on the internal display and on an external monitor. As the user who started the thread in April 2008 wrote,

"I restarted my MBP last night, and it proceeded to go through the shut down process and restart. The starting chime can be heard, but there was no image on the monitor, just black. I opened the lid to start troubleshooting the issue. Blank screen on the MBP as well. I held the power button down and forced another restart, to no effect. Still a blank screen. I disconnected everything from the MBP and tried again. Still a blank screen. I've reset the PRAM, and also the Power Management setting. Still not working.

"From as best I can tell, the MBP is booting up with no problem, I just have a black screen, so the computer is currently unable to be used in any capacity. I let the computer start up, and run for several minutes. I then sent the keyboard command to log off, and I could hear the computer activity increase."

As you can see, it's a very long thread — it continues on another page.

The upshot is, this appears to be a genuine problem with the Nvidia GeForce 8600M GT graphics processor — the same one that I have. The affected machines, Apple now says, were manufactured between May 2007 and September 2008. If your machine has distorted or scrambled video, or no video on the screen, you may be eligible for a free repair (even if you're out of warranty), or even refund. Check out the details — and if you have experienced this problem, please let me know.