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tomstavrou Level 1 Level 1 (0 points)
I am using a Macbook Pro 2.4MHz Intel Core 2 Duo, 4GB 1067MHz DDR3.
That's the one with the Nvidia GeForce 9400M and the Nvidia GeForce 9600M GT.
Using the Nvidia GeForce 9400M, as my default video card, seems to make my screen blinks. That is random.
Apple's Hardware Test show no problems.
When I am using the Nvidia GeForce 9600M GT the screen blinks stops.
I am sure that all started after updating to Mac OS X Snow Leopard. I am currently running Mac OS X 10.6.5.
Is this a software problem or there is a problem with the Nvidia GeForce 9400M chip?
Does any is experiencing the same problem?

+the problem withe the screen blinking is quite old. I am mostly using my Nvidia GeForce 9600M GT as my default video card with no problem at all, but I want to be able to use my Nvidia GeForce 9400M because of the better battery life.
Any help will be valuable.+


Macbook Pro 2.4MHz Intel Core 2 Duo, Mac OS X (10.6.5)
  • Fernando Iglesias Level 1 Level 1 (0 points)
    I've got the same issue. I'm trying to find out what's happening. If I find any explanation or solution, I'll post it here.

  • Tu333 Level 1 Level 1 (0 points)
    I don't actually have this problem, but I am a newbie when it comes to the finer points of using OS X. I have the 15" 3.06GHz Core 2 Duo and it seems to be using the 9400M for both my laptop screen and my external monitor. How did you change the default video card to the 9600M GT?
  • Fernando Iglesias Level 1 Level 1 (0 points)
    System Preferences>Energy Saver>Higher performance
  • Hammie14 Level 1 Level 1 (5 points)
    I have the very same problem with my MPB.

    I took my Mac in to the apple store where I was told the problem was the logic board (this is the main PCB inside the computer with the display chip on).

    Apple are replacing the logic board inside my computer as they have seen the problem before!

    I do have apple care and its all covers for me so i am not paying for the repair, but have been told if you dont have applecare this could be up to £800 pound to repair! Ouch......

    Hope this helps
  • RandyOo Level 1 Level 1 (0 points)
    You might want to have a look at this thread:

    Lots of folks have had lots of hardware replaced, but it's hard to nail down what's at fault. My best guess is that it's either a faulty chip on the logic board, RAM, or a driver problem.

    Personally, I've been living with this issue for over a year, and find it almost tolerable using GfxCardStatus to switch GPUs without logging out. I use 9600 when I'm plugged in, and switch to 9400 when running on battery, and just put up with the blinks, as they relatively rare when I'm not running CPU intensive applications.

    Good luck...
  • jorrelemargi Level 1 Level 1 (0 points)
    Join the club mate. The flickering happens only when on 9400 card. The battery goes a long way with that card...

    but if you are willing to switch to the 9600 card (by setting your energy settings to "better performance" the blinking goes away, but then my system freezes completely at random...

    I was considering buying an iMac, but after this I'm going back to PC unless it's solved in a timely manner. There's just too many people having this problem just to ignore it.
  • coolerdad Level 1 Level 1 (0 points)
    Same problem with mine (late 2008 model.) Higher performance in energy saver, makes 'blinking' go away, but my fan seems to kick in after short time of use.
    Just called apple tech support - said known issue will repair under my extended warranty. Not sure if covered otherwise if out of warranty.
  • bdrums83 Level 1 Level 1 (0 points)
    Agreed, I have the same issue with the 9400 card, but I rarely go without a place to plugin so I strictly stick with the 9600 under high performance. You could turn your screen brightness down as far as you can handle to conserve on battery, and depending on if you're using the net or not, you could shut off Airport to also conserve battery.
  • mguertin Level 1 Level 1 (0 points)

    I have the same issue with mine and sadly I missed the date to get Applecare on this machine (they usually call but this time around they didn't).  ***** that I didn't get this resolved before my warranty ran out .. I'm certainly not going to shell out for a replacement motherboard out of pocket.  I now use the 9600 graphics exclusively and can almost watch my battery drop by the minute.


    On a side note I'm not very impressed with the quality control Apple has had with their portables in the last few years.  I bought this unit refurbished and it took two units to get one that worked properly, and even then this one never did as it's had this video blinking issue since day one.  The problem is I didn't really notice it until recently when I started using it running more often on battery and decided to use the mobile chipset to save battery time.  This is the third MBP I've had and their 3rd MBP that's had motherboard issues.


    When it comes time to replace this one I'm seriously considering going with a macbook air or something else.  Can't justify spending the money on more MBP's with such terrible track records.

  • Sam Rowlands Level 1 Level 1 (5 points)

    Did the replacement logic board solve the problem for you?

  • Shawn Mason Level 1 Level 1 (0 points)

    I am experiencing an issue with my display appearing to be in halftones. I have tried switching between the 9400M and 9600M to no avail.


    However, if i use the mini display port to attach an external display, the resolution becomes fine. I can then unhook the external display and my laptop display is perfect (until a reboot) then the problem resurfaces.

  • Sam Rowlands Level 1 Level 1 (5 points)

    Touch wood, my MBP pro has been fine since I did a clean install of Snow Leopard, which was a couple of months ago. If you have an external HD, I'd suggest copying everything to the external hard disk. Then use Disk Utility to erase the disk and install Snow Leopard from a Snow Leopard install DVD.


    Once you've got a clean OS, then do some tests to see if it solved your problem before re-installing your software, incase it's a third party product screwing something up.


    I also haven't encountered the issue with Lion, which I installed over my working Snow Leopard partition.

  • nex0 Level 1 Level 1 (0 points)

    i'm having same problems for two years now.


    Sam, I've installed clean Snow Leopard several times and the problem is always there. Even i tried with Lion, but my computer start working really slow.


    I'm glad to finally read that is not only my problem, cause that means is something wrong with our computers.

  • Sam Rowlands Level 1 Level 1 (5 points)

    Sorry to hear that a clean install didn't solve your problem.


    You could try taking it to an Apple Store, however when I tried they wanted to hold on to it until the error showed up, even though I had provided them with video and console logs of the fault. Which I thought was rediculous as sometimes the fault would show in minutes, days or even weeks.


    In reagrds to Lion being slow, I found that doing a clean install of Lion (creating a bootable USB stick first and then installing from there) made Lion so much faster for me.

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