Detects wrong display at startup

I am running 10.5 and every now and then on start up my MBP will detect a VGA display and mess up the resolution of the screen. I have to restart and then it will work again and return to my normal display mode. I do not have another display connected when this happens... can anyone explain or tell me how to avoid this annoyance from occurring every now and then?

The discussion thread http://discussions.apple.com/message.jspa?messageID=3601941 shows that the problem is over a year old with (as far as I know) no resolution.
I've asked Applecare about it two or three times. One suggestion: use compressed air to try to get dust out of the DVI port. This is a little risky because you don't want to be blowing lots of air into the computer. So you want to angle the compressed air so as to blow across the port. That said, this didn't help me.
Another suggestion: repair permissions *from the install DVD*. When I did this, I indeed noticed that some ATI-related kernel extensions needed to have the executible flag set. That said, the problem recurred not long after.
So I'm still living with it.
Note though: In my experience, you don't need to reboot to fix the display mode; you only have to sleep and then wake from sleep. It might take two or three times. In the aforementioned thread, I said that "detect displays" would work, but that broke with Mac OS X 10.4.9 or 10.4.10 , though that may be because I typically use a nonadmin account.
One last comment: as I recall, someone on the aforementioned thread had their logic board replaced as a result of this problem. I had my logic board replaced for a different reason, and it didn't eliminate this problem. So I think the logic board can be ruled out as the problem.

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Mac Mini does not detect DVI display on startup

Okay, I have a Pre 2009 Mac Mini 2Ghz Core 2 Duo. My monitor is a Westinghouse Digital LCM-22w3. The display is hooked up through DVI. When I start or restart the mac, it seems that it does not detect the display is plugged in. I have to wait for OS X to finish booting to either put the mac to sleep and bring it out of sleep or unplug the DVI cable and plug it back in to get the display on. If I hook the display via VGA using the VGA to DVI converter there is no problem. I have tried resetting the NVRAM but that does not fix the problem. I would like to get this fixed so I don't have to switch cables to be able to boot my boot camp windows install. Any help is appreciated. Thanks!

Following some investigations the problem appears to be with the power saving features of the monitor.
The MAC mini knows that the monitor is connected but the monitor puts itself to sleep.
The problem appears only when you use a single link DVI-D cable.
These are the ones with two blocks of nine pins with one large blade.
If you use a Dual link DVI-D cable (twenty four pins and one blade) the problem resolves itself and the display is active from power on.
It looks like the mini or the monitor is using one of the pins from the middle block of six for some reason.
Anyway, good look with this, I had a couple of spare DVI cables from when I was trying to get my original G4 mini working with my TV.
Regards
Gavin

Mountain Lion doesn't detect displays on startup

I use my MacBook Pro extensively in clamshell mode, and when I did this in Lion, the integrated screen would stay off whenever I turned onb the computer because the lid was closed. However, in Mountain Lion, the screen stays on despite the fact that the lid is closed. Is there anyway to force my Mac to detect displays on start up?

Go to Sys Prefs > Displays > (hold Option) and a "Detect Displays" button will appear at the bottom right. The problem for me it's that even though a display is connected and I managed to get the button to show up, it still didn't detected the display until I unplugged and oplugged back again from the thunderbolt port.

Imac running Yosemite won't detect external display

I previously was using a 2008 iMac desktop and running OS X Yosemite. I was using dual monitors (other monitor being Insignia brand) and everything worked fine. Since this was an earlier mac version, I was using the Mini DVI to VGA Adapter to connect. Last week, I got a brand new iMac (Mid 2014 version). I am running OS X Yosemite as well, but now it won't detect any displays. I'm now using the Thunderbolt cable to connect so I wonder if that has anything to do with it. But I have used that same Thunderbolt cable before on my macbook and it worked just fine.
I've tried restarting, resetting the PRAM and everything. I don't know what else to do. Help!

Thanks for the reply, but tried everything and it still won't work. Rebooted, installed updates, cleared PRAM, everything. It will not detect the displays at all. Maybe there is something wrong with my VGA cable.

MacBook no longer detects external display

When I hook my computer up in my home office I connect an external display using the Apple VGA dongle.
Previously, when I inserted the dongle the display would blank out for a moment while detecting the display, then reappear with the VGA output enabled. This is no longer the case. When I insert the dongle, my screen doesn't blank out, and the VGA output will not enable. Its like it doesn't even know I'm inserting the dongle.
I have inspected the dongle for broken pins and dirt, but it appears to be making a good connection.
Is there something wrong with my Mac, or is it the dongle? Is it worth taking this to a genius bar in hopes they can try a different dongle, or shed some light on the situation? Thanks in advance.

Try plugging the display in and then going to System Preferences>Displays and clicking the "Detect Displays" button.

MacBook suddenly won't detect my display, Using Mini Display Port to VGA?

MacBook suddenly won't detect my display, Using Mini Display Port to VGA?

dohdoh1985, I have the exact same problem also! I recently bought a 42" RCA LCD TV. I connected my MacBook Pro to my TV using a Dynex Mini DisplayPort to HDMI adapter that I got from BestBuy. It worked great until I upgraded to Mac OS 10.6.4 and then it suddenly stopped working. Same TV, same settings, same cables, same adapter. Nothing changed since the last time it worked except that my OS was upgraded to 10.6.4, so i am assuming that is the culprit. The symptoms are EXACTLY the same as what dohdoh1985 described; when I plug in the TV, the laptop display flashes (3 times) as though it is detecting an external display and the picture on the TV briefly goes from blue to black for about 1 second then back to blue. The TV does not appear in the display menu / control panel and there is no sign that the MacBook detected it. I went through the usual troubleshooting steps (reset PRAM, checked connections, tv settings, etc) but nothing worked. Other HDMI sources (i.e. Blu-ray player) work fine on the TV using the same HDMI cable on the same port so there is nothing wrong with the cable, the TV or the TV's input settings.
Meanwhile, I can still connect my MacBook to my external ViewSonic monitor at work without any problems. It's just the TV that's not working.
I cancelled my cable subscription a while ago since I only watch shows online nowadays and this was my only way of watching TV shows, so I'm quite upset.
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AMD Radeon 7950 can't detect 2nd display.

Hi, I got a new graphics controller installed today, a Sapphire 7950. Everything seemed to be running fine when starting up my PC. Only when I wanted to connect a second screen, it wouldn't be detected.
I tried connecting the first screen as second, tried different ports (DV-i, mini DP, HDMI) but it would only detect one display.
My system specs are as follows:
Processor 2 x 2,66 GHz Dual-Core Intel Xeon
Memory 11 GB 667 MHz DDR2 FB-DIMM
Graphics AMD Radeon HD 7950 3072 MB
Chipset Model:          AMD Radeon HD 7950
Type:          GPU
Bus:          PCIe
Slot:          Slot-1
PCIe Lane Width:          x16
VRAM (Total):          3072 MB
Vendor:          ATI (0x1002)
Device ID:          0x679a
Revision ID:          0x0000
ROM Revision:          113-E2080C-101
EFI Driver Version:          01.00.624
Displays:
Display:
Resolution:          1920 x 1080
Pixel Depth:          32-Bit Color (ARGB8888)
Main Display:          Yes
Mirror:          Off
Online:          Yes
PCI cards:
Name:          ATY,Hamachi
Type:          Display Controller
Driver Installed:          Yes
MSI:          No
Bus:          PCI
Slot:          Slot-1
Vendor ID:          0x1002
Device ID:          0x679a
Subsystem Vendor ID:          0x174b
Subsystem ID:          0xe208
Revision ID:          0x0000
Link Width:          x16
Link Speed:          2.5 GT/s
Name:          ATY,HamachiParent
Type:          ATY,HamachiParent
Driver Installed:          No
MSI:          No
Bus:          PCI
Slot:          Slot-1
Vendor ID:          0x1002
Device ID:          0xaaa0
Subsystem Vendor ID:          0x174b
Subsystem ID:          0xaaa0
Revision ID:          0x0000
Link Width:          x16
Link Speed:          2.5 GT/s
Any ideas of what could be wrong or missing?
Thank you,
Hengbo

A closer reading of the safire 7950 Mac edition site (link above) says they want to see a Mac Pro 4,1 2009 or better.
System Requirements
Mac Pro with Mac OS X 10.7.5
CD-ROM or DVD-ROM drive for installing software
Mac Pro with Mac OS X 10.8.2 or later
2 GB RAM, Early 2009 Mac Pro (MacPro4,1)

Not Detecting External Display - 24" Gateway FPD2485W

Hi everyone,
I'd really appreciate any help I can get on getting my monitor to display at 1920x1200.
My setup:
Mac Book Pro 2.2Ghz
4Gb memory
128 M video memory - NVidia GeForce 8600M GT Memory Card
OSX - 10.5.2
Bios - MBP 31.0070.B05
External Display - 24" Gateway FPD2485W
What I've tried... all manner of plugging in the display, then booting up, then laptop then powering up display. I've applied the latest bios. I've run apple-opt-P-R at startup.
I haven't yet been able to get it to detect this display. Can anyone confirm that the 128M card can handle the local display plus a 1920x1200 display? From what I've read, I believe this is possible. Anybody got any other suggests for me to detect the monitor and set a display resolution higher than 1440x900?
Thanks,
Alan

Hi Mac Wise,
Thank you for your response.
I am using the DVI connection and it displays normally, but just can't detect the monitor. It gives me the default 15" MBP resolutions... do you get different behavior? I can't go higher than 1440x900.
Thanks,
Alan

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Hello,
I have a strange problem: Sometimes EFI loads OS-X with wrong display resolution which ends into a crash of loginwindow.app.
Let me explain it in more details: First I had a system with rEFIt. Everything worked like a charm ... until on some day (I think it was EFI Update 1.5.1, but I don't know it exacly) my mbp rev3 sometimes decided to show EFI menue much larger as you would expect it on a 640x480 display. This happens in about 3 of 4 boots. If this happened, OS-X crashed while loading loginwindo.app and Windows crashed before showing the windows loading screen.
Then after talking with some guys in irc unofficial support I reinstalled everything because they said all my 3rd parity software could be the reason for this error. Now I have a fresh installed leopard and the error still occures - and the error also occures when I boot into leopard disc.
*To describe the problem in a few words:*
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*I tried following things to fix the problem:*
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- single user mode: did't find something in logs, but I also didn't find an efi log
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- plug off all external usb devices: no effect
Now I really don't know what to do, I don't even have an idea where to find this error and what to try next. The mbp is my only computer, so I would find it excellent to solve the problem for myself.
Thanks for any help what to do
Message was edited by: TheInfinity

I'm not sure why you're password is wrong when you type it directly in your station, but I have found something related to remote logging.
I had always gotten the password wrong when I tried to connect through VNC from my Linux to my Mac. The problem is that for some reason, my keyboard layout is applied twice. I'm using the colemak layout, so if I want to type 'K', I need to click on the key that is marked 'N' in QUWERTY keyboard.
BUT, through VNC to my mac, if I want to type 'K', I need to type the key that is mapped to 'N' on colemak layout, which is the key marked 'J' in QUWERTY.
So to type hello, through normal colemak, I would click on hkuu;, but through VNC to the mac, I need to click on hniip.
Here's the map that can be used to generate the above:
Qwerty -> Colemak
k -> e
n -> k
j -> n
e -> f
h -> h
u -> l
; -> o
p -> ;
i -> u
My solution was to find out how my password should be typed with double-applied colemak, then after log in, change the keyboard layout to QWERTY, and then it is applied only once and I can type in normally. I'm not sure what's the cause of the bug, but at least you have something to try..

HT5167 after I updated to 10.7.4 my macbook pro 2011 doesn't detect external display anymore what should I do?

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after I updated to 10.7.4 my macbook pro 2011 doesn't detect external display anymore what should I do?

Not detecting external display after waking up MBP from sleep mode

I am a recent owner of a MBP and enjoying it. However, one problem that I can't seem to find a solution to is the external display problem after sleep mode.
When I first boot up the Mac and plug in my Dell external monitor via the mini adapter, there is no problem with detection or display. However, every time I put the MBP in sleep mode and then wake it up again, the external monitor does not "wake" up and my MBP only displays my normal screen on the Mac.
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Although this is a quick fix in itself, I do not want to wear out the mini port by doing this every timeI come out of sleep mode. Any solutions so that the external monitor will detect the MBP waking up from sleep and display properly? Thanks!

And same problem here.
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ATI Radeon 4870 won't detect second display

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Hi,
When i connect my Early 2011 MBP to an external display i get a garbled display at startup.
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Welcome!!
It could be that you are using the external in "mirrored mode" with the res set above the max res for the MBP screen. On my Late 2007 MBP, the F7 key toggles between mirrored mode and "spanning" (or "extended desktop") mode and System preferences will let you set the two displays independently. I use an external monitor in spanning mode and have not experienced a problem as I have the internal display prefs set to a comfortable res for its hardware.

Detects wrong display at startup

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