External Display only with VGA Adapter working

Question

Hello, I'm german so sorry for my bad english
After updating to Leopard 10.5.2 and installation of the Leopard Graphic Update, my external Display isn't working with DVI anymore. If I plug it in, my desktop flashes and I also get the monitor information tab of my external Display (Name and Settings correct). But the Screen stays black as in power saving mode. If I use the DVI -> VGA Adapter, everything works fine...
Could that Problem be realted to the new Updates?
I've also checked every hint of that Forum (PRAM reset, deleting Preference Files, trying to boot with closed MBP, ...), nothing worked for me. The Problem also occurs in Bootcamp! The external Display is recognized fine, but will not display any image, only if I use the Adapter.

Answer 1

According to Apple support, it is "expected behaviour" under Lion for the MBP's internal display to reactivate upon opening the lid, even if you want to use only your external display. A new version of the clamshell mode-related knowledgebase article (replacing HT3131) is due shortly confirming this.
This is despite:
- the obvious temperature-related benefits that were achievable (under Snow Leopard) by opening your MBP lid whilst continuing to output solely to a 27" cinema display
- the waste of energy and inefficient use of graphics processing power in needlessly running two active screens (ie if running your MBP in clamshell mode would otherwise make it too hot and/or noisy)
- the negative longer-term impact on the battery and other components from running the MBP hotter than it needs to be.  
If you would like to have the previous behaviour restored, please consider lobbying Apple to change how Lion handles clamshell mode. Options available to Apple include changing Lion's expected behaviour or adding a user-selectable option within System Preferences.
Feedback should be submitted here:
http://www.apple.com/feedback/macosx.html