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External Display Problem w/10.6.5

Hi, all. I'm having an odd external display issue that I can't figure out how to solve. I teach a class using my MBP, and as such have to plug it into the (VGA) projector in the classroom. Up until last week or so this worked perfectly. Now, when I plug the VGA adapter into the Mini DisplayPort, the screen flashes (as though it's detecting an external monitor), but it fails to detect the external monitor. However - and this is the odd part - if I reboot with the cable connected to the Mini DisplayPort, the external monitor is correctly detected at startup.

I tried logging out and connecting it with nobody logged in to the machine, and that didn't work; it's only on a fresh reboot that it will "see" the external display.

The only thing that I can think of that has changed is the 10.6.5 update. It seems fairly clear that my adapter still works fine, as it works correctly at startup... Anybody have any suggestions?

MBP 15" Mid-2010 Hi-Res Core i7, Mac OS X (10.6.5)

Posted on Nov 22, 2010 12:55 AM

35 replies

dmzimmerman Author

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Dec 1, 2010 2:43 AM in response to .Michel.

.Michel. wrote:
Anyway, I solved it by downloading gfxCardStatus 1.8.1 and be sure that the NVIDIA graphics card was selected. Clearly, the external monitor is not working if Intel graphics card is selected.

Hope this helps.

It doesn't, unfortunately. This was always the case before 10.6.5 - if the video card is forced to Intel-only by gfxCardStatus, external monitors do not work. I have tried every possible setting with gfxCardStatus, with no success.

Apparently, the issue is not experienced by everybody. It's been reported to Apple at this point through more formal channels (the developer bug reporter), and hopefully we'll get some resolution soon...

Dec 1, 2010 6:44 PM in response to dmzimmerman

I've got an early 2010 macbook pro and I've been using and external monitor (hdtv.) lately, my tv is no longer detecting my mac and i've noticed that in preferences under display resolution options- my options have lessened. there is no resolutions with refresh rate choices (60hz or 120hz.)

ive replaced all my cables and tried another tv. do i need to reinstall osx?

TristanV

Level 1

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Dec 2, 2010 12:38 AM in response to dmzimmerman

I experienced the same problems and downgraded to 6.4 but no solution.
The problem is the VGA. With DVI (to Projector) and DVI/HDMI (to the external screen) everything works fine. What is really strange that this phenomenon occured from one moment to another...

eww

Level 9

53,028 points

Dec 2, 2010 8:39 AM in response to TristanV

Further evidence that 10.6.5 is not the problem.

moreiraj

Level 1

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Dec 2, 2010 8:56 AM in response to dmzimmerman

The problem is the 3rd part mdp to VGA adaptor!
I have proved with an apple adaptor and now i can display my presentations at all projector of my University.

Apple mf!

Anyone wants to buy a 3rd part adaptor?

eww

Level 9

53,028 points

Dec 2, 2010 8:59 AM in response to moreiraj

Anyone wants to buy a 3rd part adaptor?

...that doesn't work?

Boy, that's an attractive offer. But I think I'll pass, thanks. 😉

Dec 2, 2010 5:56 PM in response to eww

Everybody have their power management settings adjusted? This just solved my external video problem after I'd practically everything: http://learntoduck.com/techsupport/dual-link-dvi-adapter-macbook-pro

Dec 3, 2010 10:58 AM in response to moreiraj

I tried my 3rd-party adapter and an Apple-branded adapter, and I can confirm that the Apple one worked without a restart, and the 3rd-party adapter would only work after a restart.

Dec 4, 2010 7:27 AM in response to dmzimmerman

I found that switching the "Energy Saver" preferences to "Higher Performance" solved my display issues on a 2009 MBP. My recollection is that the energy saver preferences change how the video chipset operates in order to save power.

Previously, I was not able to run my external monitor at the highest (native) resolution in VGA, but found it was fine when using DVI. After I fiddled with the energy saver prefs, the monitor worked in native resolution (1600x1050) in both VGA and DVI.

-g.

Dec 7, 2010 4:20 AM in response to dmzimmerman

I have also seen issues detecting an external monitor with 10.6.5. With a third-party Mini DisplayPort to HDMI adapter and upgrading to 10.6.5 I can no longer boot. It hangs in a blue screen trying to detect the monitor for a long while until I unplug it. Then, the screen comes back to the main display but the system was unresponsive.

Coming out of sleep, the system stays for a long while at the blue screen but detects the monitor and continues.

Without anything except the main screen plugged into the DVI connector on the Mini I do not see any blue screen or issues detecting the screen. It instantly comes out of sleep.

My next step will be to replace the third-party video adapter which is easier than backing out of 10.6.5.

Sini76

Level 1

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Dec 9, 2010 1:24 AM in response to dmzimmerman

Hi, all.
My problem is similar to yours,but weirder, after i've connected my MBP to external Tv (Sharp Acquos 32")with an 3rd part dvi/vga adapter, it's not recognized the model of external monitor and don't switch the resolution to 1024x768(the max possible with vga connection) but set up all resolution of Tv Sharp and Lcd screen of MBP to 640x480, also i've disconneted the external Tv, but the resolution remain the same.
I've tried everything change resolution with/without Tv connected, shutdown and restart MacOs with/without Tv, but nothing...
The result of all my attempts is that my MBP lcd screen work fine only with the Hdmi adapter inserted, but when i unplug it, the screen return to 640x480 resolution.
I hope my explanation was sufficiently clear, english is not my native language, i think we both understand.... 😉

Could someone help me? ...please.
Thanks a lot.

Dec 9, 2010 2:38 AM in response to dmzimmerman

Got the same problem with my MacBook Pro i7.

After the update, I need to restart before it detects my SONY TV.

Worked before the update.

csiewap

Level 1

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Dec 16, 2010 7:29 AM in response to dmzimmerman

I have try to reset the SMC, and it seem to solve the problem for me.

http://support.apple.com/kb/ht3964

kerenSun

Level 1

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Dec 21, 2010 9:18 PM in response to dmzimmerman

I had the same problem. My MBP is ok to connect with external LCD display or flat TV via MDP2VGA dongle but no luck with any projectors. The screen on the mac just went blue for seconds then back to normal without recognizing the projector. I called the Apple service guys, they told me they have noticed this problem but no solution at the moment(you can reboot your mac with the project connected, if you call that a "solution"). They also said they have reported this issue to the product department and a patch will be released someday (god knows when).

leonaral

Level 1

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Jan 8, 2011 3:49 AM in response to kerenSun

Hi all ! Apple has released a new Mac OX 10.6.6...

Does anybody know if it fixes the issue?

I had a bad experience when upgrading from 10.6.4 to 10.6.5. If this new SP does not fix the external display problem, I will not upgrade.

External Display Problem w/10.6.5