IMac not detecting external displays

I have a mid-2010 iMac which, for a long time, ran with a Samsung TV as a double monitor through the mini displayport (via a VGA adapter). This past Christmas, I received a Yiynova MSP19U artist's tablet, which also uses a VGA connector. After installing the drivers and everything, it connected and worked just fine. However, every time the iMac would go to sleep (or the monitor was disconnected and reconnected), it would stop recognizing the external monitor. I would have to shut the whole thing down and reset the PRAM. Usually, after doing that a few times, unplugging and replugging, it would recognize it again. However, yesterday, it disconnected, and now it won't reconnect. I've cleared the PRAM multiple times, I've cleared the SMC, I've unplugged both devices and all peripherals and then turned them all on together and separately. I've also tried to connect another monitor that uses VGA, but still, nothing is connecting. I've connected the tablet to my wife's PC, and it works just fine. I'm at my wit's end with this whole thing. Does anyone have any other potential solutions, or do I just need to take it to the Genius Bar?
Another issue may be that after it disconnected yesterday, it needed a software update restart, which I allowed (an update for Mountain Lion, which is what I'm running on the computer). I don't know if that would've affected anything.
Thanks for the help.

You have done some of this already.
Video Troubleshooting Internal and External Monitors

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skn2011 wrote:
My Macbook Pro notbook 13.3" does not detect external display throught it's mini display port to HDMI connector when connected to Sony Bravia 32" LCD TV.Can anyone help me get the answer as i tried reading everywhere on internet and none does not seems to work.Please help me out guys.
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Macbook will not detect external display

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Did you have any luck resolving this? I have had exactly the same issue when updating the EFI Firmware to Version 2.8 (the latest for a Mid-2013 MacBook Air 6.2 model) - MBA61.0099.B12
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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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And same problem here.
Using a MBP 2.66 i7 with a Dell 3008WFP that's connected to the MBP through DisplayPort. It works some of the time but once in a while (only been using the new MBP for a couple of days now) the monitor won't come out of sleep mode. Turning it off/on causes OS X to completely ignore the monitor. I was able to get this setup to work again by pressing 'Detect Displays' in the System Preferences pane but most of the times that doesn't help. The only sure way to get the monitor working again is by booting into Windows through Bootcamp, Windows is able to use the monitor, if I reboot after that OS X sees the monitor again.
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MBP not detecting external display

I encountered a strange problem today when I tried re-connecting my external monitor: it is not being detected by OS X.
I tried everything I could think of; I selected "detect displays" in preferences, I restarted the computer, I dis- and re-connected everything, I reset the PRAM, I tried connecting to a different monitor, and nothing seems to work. When I disconnect and reconnect the DVI cable, the laptop's screen flashes blue like it normally does, but nothing appears on the external monitor's screen. For the record I'm using the Dell 2209WA, and I haven't had any problems like this yet.
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Hi everyone,
I'd really appreciate any help I can get on getting my monitor to display at 1920x1200.
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4Gb memory
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Macbook Pro not detecting external display

I can't seem to make this work. I'm using a MiniDP-DVI cable which is plugged into an DVI cable plugged into an external monitor. I know it works because I have tried it on other computers and it has worked on the Macbook (erratically).
I've reset the PRAM several times and it has not fixed the problem. I did it in this order:
1. Remove adapter from computer
2. Shutdown
3. Press Option Command P R until the second chime is heard.
4. Log on as usual
5. Reconnect adapter to MBP
This is what the system log states when I plug the adapter in:
Oct 27 20:47:01 SMBP.local WindowServer[80]: Received display connect changed for display 0x42732c0
Oct 27 20:47:01 SMBP.local WindowServer[80]: Created shield window 0x66 for display 0x042732c0
Oct 27 20:47:01 SMBP.local WindowServer[80]: handle_will_sleep_auth_and_shield_windows: no action for lock state 1
Oct 27 20:47:01 SMBP.local WindowServer[80]: Received display connect changed for display 0x3f003d
Oct 27 20:47:01 SMBP.local WindowServer[80]: Received display connect changed for display 0x3f003e
Oct 27 20:47:01 SMBP.local WindowServer[80]: Received display connect changed for display 0x3f003f
Oct 27 20:47:02 SMBP.local WindowServer[80]: Display 0x042732c0: GL mask 0x1; bounds (0, 0)[1280 x 800], 9 modes available
          Main, Active, on-line, enabled, built-in, boot, OpenGL-accel, Vendor 610, Model 9ccb, S/N 0, Unit 0, Rotation 0
          UUID 0x0000061000009ccb00000000042732c0, ColorProfile { 3, "Color LCD Calibrated 2012-06-28"}
Oct 27 20:47:02 SMBP.local WindowServer[80]: GLCompositor: GL renderer id 0x01024301, GL mask 0x0000000f, accelerator 0x00004333, unit 0, caps QEX|QGL|MIPMAP, vram 451 MB
          texture units 8, texture max 8192, viewport max {8192, 8192}, extensions FPRG|NPOT|GLSL|FLOAT
Oct 27 20:47:02 SMBP.local WindowServer[80]: Display 0x003f003f: GL mask 0x8; bounds (2304, 0)[1 x 1], 1 modes available
          off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 3, Rotation 0
          UUID 0xffffffffffffffffffffffff003f003f
Oct 27 20:47:02 SMBP.local WindowServer[80]: Display 0x003f003e: GL mask 0x4; bounds (2305, 0)[1 x 1], 1 modes available
          off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 2, Rotation 0
          UUID 0xffffffffffffffffffffffff003f003e
Oct 27 20:47:02 SMBP.local WindowServer[80]: Display 0x003f003d: GL mask 0x2; bounds (2306, 0)[1 x 1], 1 modes available
          off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 1, Rotation 0
          UUID 0xffffffffffffffffffffffff003f003d
Oct 27 20:47:02 SMBP.local WindowServer[80]: Created shield window 0x68 for display 0x042732c0
Oct 27 20:47:02 SMBP.local WindowServer[80]: Created shield window 0x69 for display 0x003f003f
Oct 27 20:47:02 SMBP.local WindowServer[80]: Created shield window 0x6a for display 0x003f003e
Oct 27 20:47:02 SMBP.local WindowServer[80]: Created shield window 0x6b for display 0x003f003d
Oct 27 20:47:02 SMBP.local WindowServer[80]: Display 0x042732c0: MappedDisplay Unit 0: Startup Mode 1280 x 800, CGSThirtytwoBitColor, Resolution 1, IOMode 0x80000000, IODepth 0x0, IOReturn 0x0
Oct 27 20:47:02 SMBP.local WindowServer[80]: Display added
Oct 27 20:47:02 SMBP.local WindowServer[80]: Display removed
Oct 27 20:47:02 SMBP.local WindowServer[80]: Display 0x042732c0: GL mask 0x1; bounds (0, 0)[1280 x 800], 9 modes available
          Main, Active, on-line, enabled, built-in, boot, OpenGL-accel, Vendor 610, Model 9ccb, S/N 0, Unit 0, Rotation 0
          UUID 0x0000061000009ccb00000000042732c0, ColorProfile { 3, "Color LCD Calibrated 2012-06-28"}
Oct 27 20:47:02 SMBP.local WindowServer[80]: GLCompositor: GL renderer id 0x01024301, GL mask 0x0000000f, accelerator 0x00004333, unit 0, caps QEX|QGL|MIPMAP, vram 451 MB
          texture units 8, texture max 8192, viewport max {8192, 8192}, extensions FPRG|NPOT|GLSL|FLOAT
Oct 27 20:47:02 SMBP.local WindowServer[80]: Display 0x003f003f: GL mask 0x8; bounds (2304, 0)[1 x 1], 1 modes available
          off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 3, Rotation 0
          UUID 0xffffffffffffffffffffffff003f003f
Oct 27 20:47:02 SMBP.local WindowServer[80]: Display 0x003f003e: GL mask 0x4; bounds (2305, 0)[1 x 1], 1 modes available
          off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 2, Rotation 0
          UUID 0xffffffffffffffffffffffff003f003e
Oct 27 20:47:02 SMBP.local WindowServer[80]: Display 0x003f003d: GL mask 0x2; bounds (2306, 0)[1 x 1], 1 modes available
          off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 1, Rotation 0
          UUID 0xffffffffffffffffffffffff003f003d
Oct 27 20:47:03 SMBP.local WindowServer[80]: **DMPROXY** (2) Found `/System/Library/CoreServices/DMProxy'.
Oct 27 20:47:03 SMBP.local WindowServer[80]: Display 0x042732c0: MappedDisplay Unit 0; ColorProfile { 3, "Color LCD Calibrated 2012-06-28"}; TransferTable (256, 3)
Oct 27 20:47:04 --- last message repeated 1 time ---
Oct 27 20:47:04 SMBP.local WindowServer[80]: **DMPROXY** (2) Found `/System/Library/CoreServices/DMProxy'.
Oct 27 20:47:04 SMBP.local WindowServer[80]: Display 0x042732c0: MappedDisplay Unit 0; ColorProfile { 3, "Color LCD Calibrated 2012-06-28"}; TransferTable (256, 3)

I had the exact same behavior and log and I solved the issue by replacing the MiniDP-DVI adapter. I tried the "broken" adapter on another set of laptop+display and it was working there, so that made me think the adapter was ok, when apparently it was not.

Imac running Yosemite won't detect external display

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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.

My mid-2010 10.8.2 iMac won't detect external displays.

My mid-2010 10.8.2 iMac won't detect external displays. I've tried using a third-party minidisplay port to DVI adapter, as well as an Apple-brand minidisplay port to VGA adapter. The monitor I'm using is a Dell SP2008WFPt. It is a functional monitor. I've tried resetting the PRAM, repairing my disk permissions, rebooting, and doing all sorts of wacky stuff with the order I plug things in. Is there a solution? It seems like lots of folks are having the same problem.
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If 10.7.0 or later...
Bootup holding CMD+r, or the Option/alt key to boot from the Restore partition & use Disk Utility from there to Repair the Disk, then Repair Permissions.
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Can I connect to iMac 27" as external display?

I'm considering buying 2 iMac 27" to run Windows 7.
Can I connect these two together so iMac 1 can use iMac 2 as external display and visa versa.
In other words... is the mini display port both for input and output?
If yes... does this work under Windows 7 as well?

tjementum wrote:
I just love Mac hardware, and an iMac (two in my case) on a desk is just such a nice clean setup, with only one cable. Just counted 16 cables for my current PC mini tower setup with 2 screens - don't ask
Just so you know, I'm well aware of Apple's "cableless" marketing for this thing. But on my new iMac, I actually only have a single port, the FW800, that doesn't have a cable sticking out of it.
But Mac OSX is just not a nice operating system IMO
At least we can use you as an example of a 100% legitimate Mac owner of a Windows OEM install.
Anyway... I just ordered 2 x 27" iMac's. If i somehow succeeds in getting them connected in Windows, I'll post here... if not feel free to ask me, in 6 months.
Please do post back, because if someone tries it, then everyone will know if it works. I have seen reports of a PC driving the iMac display and I have done it with my MacBook Pro. I'm still not 100% sure that two iMacs will cooperate in this way. They both have the same cable connected to the same input/output port. Which one is the target? I have never heard of Windows or any PC hardware having the ability to convert a video port to input, so Windows would have to be the broadcaster. You may need MacOS X to detect the input and use it instead of trying to send out its own signal. Hopefully this won't short out the video circuitry on both.
And in 6 months when you are reinstalling Windows to clean off all the malware, you can still use the Mac machine

How do I use my 2011 27" iMac as an external display for a pc?

I just bought a 27" imac for my home, and was also planning on using it as an external display for my work Dell Laptop running Windows 7.
The Dell laptop has a displayport output, so I was planning on getting a displayport <-> minidisplayport cable, and using the iMac in target display mode.
I would simply plug the minidisplay end of the cable into one of the iMac's 2 Thunderbolt ports. Seemed fairly simple.
Except now it seems from what I have been reading that 2011 iMacs DO NOT WORK in target display mode unless they are connected to another Thunderbolt source. This leads to me two questions.
1. Can anyone confirm or deny this? If this is true, does that mean I cannot plug my Dell's displayport into the iMac's Thunderbolt port as I described above?
2. If #1 is true, is there any other option? Are there any adapters that I can use to turn my Dell into a Thunderbolt source for display purposes?
If I can't resolve this I will have to return the iMac
Thanks very much.
David

David,
Sorry you can't use the 2011 iMac as an external display to your PC. The feature you are referring to is called Target Display Mode and works on 2009 & 2010 27" iMacs. The 2011 machines use Thunderbolt as you know however they do support external displays that are not Thunderbolt displays. So for example if you wanted 2 displays on the iMac you can easily do that with either Mini Display port to DVI or MDP to VGA or even HDMI. MDP is the same size as Thunderbolt and this will work fine to drive a display, TV or even a projector.
I'd recommend reading Apple's explanations at Target Display Mode 2009 & 2010 iMacs & Target Display Mode Mid 2011 iMacs.
Using a Mac as an external display for a Windows machine to me seems like a horrible waste of a Mac. Why not enjoy the iMac and if anything run Windows on it and get rid of the PC?

Using imac as an external display. is it possible?

hi. i just bought an macbook. i would like to use my iMac as an external display for my macbook. is this possible?

ok, its not posibble but let me know if there is a way i could get around it.
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Using a 27-inch iMac as an external display for my macbook air

I would like Using a 27-inch iMac as an external display for my mac book air.
i bought a Mini DisplayPort to Mini DisplayPort cable, it's the Belkin Mini DisplayPort to Mini DisplayPort cable on apple store.
I connect my imac and mac book air with this cable but the screen of my mac book air don't appear on imac screen.
where is my error ?

Morning seal, my experience suggests the latter of your two posts is the correct one. I have a 27" iMac with a mini display port (a 2-year old one, not the newer one with thunderbolt); and a brand new Mac book air with thunderbolt. I connected the two with a Belkin male-male mini display port to mini display port cable, and it works fine - press command f2, and the iMac acts as display for the MBA.
The irony here is that the folks at the apple store in Paris assured me that this would NOT work, and that I needed to buy a €999 thunderbolt display to connect to my MBA. I thought I'd try anyway, since I had the cable to connect a MacBook pro to the iMac anyway... Glad I did.
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HT5167 after I updated to 10.7.4 my macbook pro 2011 doesn't detect external display anymore what should I do?

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

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

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.
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IMac not detecting external displays

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