Sorry in advance for the long post. I have found a few threads about external display issues on the unibody MB's, but not on the MBP. Here is the issue I have had and what I found. hopefully it saves someone time in troubleshooting this problem:
I have a 2.53Ghz (late 2008) unibody MBP hooked up to a Samsung Syncmaster 206BW LCD. While using the nvida 9600 (better graphics mode), I have no problems. However, when I switch to the 9400 (better battery mode), the external LCD blanks out for a second every 5 - 20 minutes or so.
I then brought my MBP to my office where I have an Optiquest Q20wb monitor. I hooked it up and sure enough, I did not have the screen blank out the whole day.
I checked the display settings and found an interesting tidbit - the Optiquest screen has a refresh rate of 60, where my Samsung Syncmaster 20" LCD at home shows up with a refresh rate of 59.9 (even though when I use my Mac Pro tower it shows up with refresh rate of 60). Both LCDs have the same resolution of 1680 x 1050, so I was thinking the problem stems from issues in compatibility with the LCD and the 9400 video card.
So I decided to go to the Apple Store to do some testing with a Genius with my laptop and my Samsung monitor. We hooked up my late 2008 MBP laptop in the store to the Samsung 206BW LCD and after 15 minutes, it blanked out. I told the Genius that the issue does not seem to be present with my Optiquest LCD so nVidia driver compatibility with the Samsung LCD is looking most likely.
We then decided to hook up the Samsung LCD to another MacBook Pro in the store to see what would happen (a display unit). With the 9600 card activated, the monitor performed fine. However, when we changed to "Better Battery Life" mode, activating the 9400 video card, caused the MacBook Pro to actually crash and reboot!! When it came back up, the video card setting was set back to "Bettery Graphics Performance". We checked the installed updates on the MacBook Pro and the one in the store did not have the MacBook Pro 2.1 update which fixes compatibility issues with some external displays.
It is apparent that the 2.1 update helps the laptop not crash when the 9400 card is activated while hooked up to a Samsung 206BW LCD, however, it is also apparent that the update does not solve all the issues with compatibility, as the refresh rate is detected incorrectly (59.9 instead of 60) and the screen blanks out intermittently as a result of what looks like the video card sending a refresh rate that is out of range of the monitor's capability.
They took my information and are going to escalate the issue to the engineers to hopefully get a fix pushed out as this may also affect other LCD's that are based on similar components as the Samsung displays.
Bottom line - don't bother swapping laptops if you are experiencing this issue on your external display. Hopefully a software update will be out soon. I urge you to call Apple Support, however, and report the issue so that they can get an update out faster.
For those asking why would you even need the better battery life mode turned on when using an external display since you are obviously near a power source? Well - sometimes you come in from an appointment where you had the power saver mode on and want to just get to work without logging out and closing all your apps. It is a pain to have to log out just to switch to a GPU that does not blank out on you. Oh yeah - besides that - when you pay $2500 - $3000 for a laptop, you just want the stuff you paid for to work.
I have a 2.53Ghz (late 2008) unibody MBP hooked up to a Samsung Syncmaster 206BW LCD. While using the nvida 9600 (better graphics mode), I have no problems. However, when I switch to the 9400 (better battery mode), the external LCD blanks out for a second every 5 - 20 minutes or so.
I then brought my MBP to my office where I have an Optiquest Q20wb monitor. I hooked it up and sure enough, I did not have the screen blank out the whole day.
I checked the display settings and found an interesting tidbit - the Optiquest screen has a refresh rate of 60, where my Samsung Syncmaster 20" LCD at home shows up with a refresh rate of 59.9 (even though when I use my Mac Pro tower it shows up with refresh rate of 60). Both LCDs have the same resolution of 1680 x 1050, so I was thinking the problem stems from issues in compatibility with the LCD and the 9400 video card.
So I decided to go to the Apple Store to do some testing with a Genius with my laptop and my Samsung monitor. We hooked up my late 2008 MBP laptop in the store to the Samsung 206BW LCD and after 15 minutes, it blanked out. I told the Genius that the issue does not seem to be present with my Optiquest LCD so nVidia driver compatibility with the Samsung LCD is looking most likely.
We then decided to hook up the Samsung LCD to another MacBook Pro in the store to see what would happen (a display unit). With the 9600 card activated, the monitor performed fine. However, when we changed to "Better Battery Life" mode, activating the 9400 video card, caused the MacBook Pro to actually crash and reboot!! When it came back up, the video card setting was set back to "Bettery Graphics Performance". We checked the installed updates on the MacBook Pro and the one in the store did not have the MacBook Pro 2.1 update which fixes compatibility issues with some external displays.
It is apparent that the 2.1 update helps the laptop not crash when the 9400 card is activated while hooked up to a Samsung 206BW LCD, however, it is also apparent that the update does not solve all the issues with compatibility, as the refresh rate is detected incorrectly (59.9 instead of 60) and the screen blanks out intermittently as a result of what looks like the video card sending a refresh rate that is out of range of the monitor's capability.
They took my information and are going to escalate the issue to the engineers to hopefully get a fix pushed out as this may also affect other LCD's that are based on similar components as the Samsung displays.
Bottom line - don't bother swapping laptops if you are experiencing this issue on your external display. Hopefully a software update will be out soon. I urge you to call Apple Support, however, and report the issue so that they can get an update out faster.
For those asking why would you even need the better battery life mode turned on when using an external display since you are obviously near a power source? Well - sometimes you come in from an appointment where you had the power saver mode on and want to just get to work without logging out and closing all your apps. It is a pain to have to log out just to switch to a GPU that does not blank out on you. Oh yeah - besides that - when you pay $2500 - $3000 for a laptop, you just want the stuff you paid for to work.
