External monitor occasionally flickers

I haven't seen a post about a problem that seems exactly the same as mine.
My MBP is the 2010 version and is hooked up to an external monitor via DVI. The problem is that the screen briefly shakes, lasting no more than half a second. It does it sporadically with no regular pattern-sometimes its two hours between when it does it, other times its five minutes. It isn't a huge problem in terms of usability, but I paid too much for this computer to have a problem.
I know it isn't the monitor or the cables because I've tried different monitors and cables, including using different mini-DV cables.
Thanks!

How did you setup your display preferences? Under the arrangement tab, it will differ on which one is your main viewer. Not to mention where (which monitor)your tab menu is set. Do you have the right adapter for your external monitor?
When does it blink; when your starting up? Jon
I did go throught the display preference. The external monitor is located to the right of the imac on the arrangement tab.
I'm not exactly sure what you are referring to with how the tab menu is set. The display tab is set to 1280x1024, millions of color, 60 HZ (other option is 75HZ).
The color tab has a defaul profile of VE710s-2 which I just used from day one.
The monitor only has an analog in (no digital), so I'm using the apple adapter for the small square plug on the back of the imac to analog. I didn't think I had any other choices (right or wrong) for that item....
wwc

Similar Messages

External Monitor Occasionally Flickering

Hello,
I have a MacBook Pro 13 Late 2011 model that's plugged into an Asus P28Q 24" IPS monitor, closed lid configuration. It runs fine for a while then will flicker randomly for a duration of a few seconds to a minute or more. I have an identical configuration running on the latest MacBook Pro 13 Retina with no issues. I switched monitors and was able to replicate the issue again on the 2011 MBP ruling out the monitors. Everything seems to be updated on the 2011. Any advise would be appreciated. Here's video of the monitor flicker. http://youtu.be/sxaMTlF5ktQ
Thanks,
Chris

Hi FitDadsRock,
Thanks for visiting Apple Support Communities.
If you've noticed unusual behavior with an external display on one MacBook Pro, the steps in this article can help:
Apple computers: Troubleshooting issues with video on internal or external displays
http://support.apple.com/kb/ht1573
I'd suggest starting with this step:
Reset the system
You can reset the Mac's parameter RAM and SMC.
Regards,
Jeremy

Flickering screen on external monitor

Hi, when I connect my 2011 Macbook Air to a external monitor, the screen of the external monitor is flickering. Tried different cables and monitors, same problem every time. So my guess is, that it's a problem with the hardware of my MB? Is it easy to fix, will Apple fix it when I'll bring it to the Apple Store? Actually, I can't live without my Macbook for a while, because of my work. The problem was always there, but it's getting worse and annoying, because I bought a new very expensive external monitor.

Same with my macbook pro 13" 7,1 (mid 2010) but also with resolution same or under 1080p

Tecra M5: External monitor flickers - grounding issue?

Hi,
I just bought a new Acer Full HD LCD Monitor (P244W) and have tried connecting it to the VGA port of my Tecra M5.
It works, but there's a noticable and increasingly annoying flickering. I tried it with both XP (SP3) and now Vista (SP1) and it happens for both. I have the latest BIOS and NVidia drivers. The actual laptop LCD screen still works fine, its just the external monitor that flickers.
To ensure there was nothing wrong with the monitor, I connected it to the VGA port on the ATI video card on my desktop pc and it displayed fine without any flickering.
After browsing the web for people having similar problems, I've narrowed it down to it being caused by my AC Adapter having a grounding problem as the flickering dissapears as soon as I disconnect the AC Adapter and just run from the battery. It the seems the common solutons to this problem are:
1) Try some different VGA cables with better shielding from interference.
I tried this and it made no difference. I tried cables both with and without the ferrite magnet/choke thingy's at both ends of the cable and the flickering remained.
2) Try different screen resolutions and refresh rates.
Tried setting some lower resolutions, but the flickering remained (besides I'd rather keep the 1920x1080 native resolution for my monitor). The NVidia driver only allows 60Hz for the refresh rate at 1920x1080, so I couldn't change this.
3) Ensure both the laptop AC Adapter and the monitor are connected to the same wall socket and are on the same power extension board.
Tried this, but didn't fix it.
4) Run an extension cable to another power circuit in my house and power the AC Adapter and monitor from this to see if its something wrong with the wall socket im using.
Tried connecting to a wall socket in my laundry, but didn't fix it.
5) Try using a different power extension board and ensure nothing else is connected on it other than the AC Adapter and the monitor.
Tried this, but didn't fix it.
6) Get a 3 prong to 2 prong adapter, so the AC Adapter is no longer grounded.
Most people on the web seem to say this fixes the problem, but I'm not sure how safe it is to leave it this way in the long run. Especially, when stories of laptops catching on fire are becoming more common.
7) Get a generic brand AC Adapter as these sometimes deal with the grounding problem better than the Toshiba AC Adapter.
Again, I'd rather avoid this option as even the generic branded ones are expensive.
8) Remove the battery and run from the AC Adapter on its own.
Tried this, but didn't fix it.
9) Fiddle about with the monitors settings.
Tried this, but none of the settings fixed it.
So, what are my options?
Is there a known cause & solution to this problem?
If my laptop is still under warranty, can I get a replacement AC Adapter or something to workaround this problem?
Thanks
Message was edited by: shaneh20
Message was edited by: shaneh20

I finally figured it out. Just for laughs and because it was the only thing I hadn't tried, I tried using a different 3 prong power cable that I had lying around, connected it to my monitor and the flickering dissapeared. *So, the power cable that came with my Acer monitor was dodgy and not my Toshy's AC Adapter like I first thought.*
I'm guessing the dodgy power cable was preventing the monitor from grounding properly, so instead it tried to ground itself using my laptop's power cable, going via the VGA cable
. This would explain why the problem seemed to go away whenever I unplugged my laptop's power cable and also why there was interference.

External monitor flickers when waking up from sleep

I use an external monitor with my new MacBook. All works well, but I have noticed that if I start using the external after the screen has gone to sleep, I sometimes get a problem on the external where the screen flickers and breaks up. If I disconnect and reconnect the Mini DisplayPort then the problem resolves, has anyone else seen this?
Tony

I have the same issue with my new macbook.
When i wake the computer from a partial sleep the screen flickers and i get line distortion through the image.
If i put the machine to sleep unplug the mini dvi adapter and replug it in and wake the computer up the problem disappears.
The issue is also intermittent doing about 3 times out of every 10 wake ups...
If anyone has any suggestions it would be great, I a using a new Dell 2208WFP monitor.

IMac early 2008 occasional screen flicker with external monitor

I am experiencing flickering with my early 2008 iMac when driving an external monitor. My Thinkpad is flawless when pushing out to the monitor.
It will be fine, but occassionaly (every 5-20seconds) the screen gives a little flicker, about 1/4 of a second in duration.
Also, sometimes, there is no flickering, it depends on what is being displayed, which makes me think video card. I am using the 2400XT and my software is up to date.
ROM Revision: 113-B2250H-259
EFI Driver Version: 01.00.259
I am thinking about trying to source a 2600pro that came on the more high end version of my iMac and swap out the graphics card. I also want to drop a 2TB hdd in it, so I figure I might as well kill 2 birds with one stone, or kill 1 iMac with 2 simutaneous upgrades if I am unlucky! (o_O)

iMacs are not designed to have the graphics cards upgraded. If your old card is bad and you feel competent to exchange it for the same one that's really your only GPU option. Apple never said the iMac GPU's were upgradeable and frankly I've never heard of anyone successfully upgrading an iMac GPU.
As far as the adaptor well you could bring your system into an Apple Store and have it checked out by a Genius, it's a free service. I don't know how to make a reservation in Japan but I'm sure you can from the Japanese Apple site. The link in the US is:
http://www.apple.com/buy/locator/service/
I'm providing that so you can look for something equivalent.

External monitor flickers when scroll on the google stock chart in Safari

Well, this sounds crazy but this is what is happening to my Retina, 15-inch, Late 2013 Macbook Pro.
I can reproduce it.
1. Go to this page in Safari (Version 7.1 (9537.85.10.17.1)): https://www.google.com/finance?q=LQD&ei=nQQ_VPj1H4ebrAHP6oDYDQ
2. Scroll the page (not the chart)
3. My external monitor starts to flicker.
I use mini display port to DVI to connect to my ASUS VE278.
Any idea? Thanks in advance!

Hi Ziang Song,
Welcome to the Apple Support Community!
I know it can be concerning when your external display is flickering and not functioning as you would expect. In this situation I recommend the troubleshooting steps outlined in the attached article.
Apple computers: Troubleshooting issues with video on internal or external displays
Cheers,
Joe

Flickering on DVI external monitor connected to 2009 Macbook

This is an ongoing an intermittent problem. At one point Apple phone support suggested that engineers are working on the problem but I haven't heard any updates.
The problem is with a 2009 macbook (13 inch) connected to an apple display (from 2008) by an apple minidisplayport to dvi connector. I don't find this kind of problem when another computer is connected to the display. The problem is unaffected by changing the brightness settings on the display.
The problem is intermittent, it occurs roughly once every five days. It typically occurs after the computer wakes from sleep. It doesn't usually occur when the macbook is first connected to the display (this suggests that it is not a problem with the minidisplayport to dvi cable) and jiggling the cable doesn't cause the problem or make it go away. The problem doesn't occur in particular when the computer is hot, it could be cool, after it is woken from sleep. There are no problems on the macbook's built in display.
The flickering is quite dramatic. Dark flashes extend from the bottom of the display sometimes 50% of the way up the screen and sometime 75% of the way up. The frequency is irregular but during an episode the flickers occur about once every one or two seconds, but sometimes there is a gap of 5 seconds. The episode will come to an end if I put the machine to sleep and wake it again (this also suggests that this is not a problem with the cable connection or the monitor).
It is difficult to get support on this issue. Since the problem is intermittent and may not occur for 5 days it doesn't make sense to try to reproduce it in an apple store. I called apple phone support and the technician recommended adjusting the brightness of the display, resetting the pram, moving some files that record configuration data for the external monitor. These didn't help. The technician acknowledged that apple is working on this problem and recommended that I call back if the problem recurred. I called back a couple weeks later and a technician recommended that I buy another minidisplayport dvi connector - to be frank this is an inconsiderate suggestion for a problem with end to end apple hardware - and I don't expect it to solve the problem.
How should I troubleshoot this problem, or get effective help from Apple? Is this a problem with the graphics card?
John

Hello, i have the same kind of issue.
75% of the time, my external screen works fine, otherwise, i need 5-10 plug/unplug/reboot to make it work...
There my windowserver.log from this morning :
Jul 28 09:40:00 [52] Server is starting up
Jul 28 09:40:01 [52] CGXMappedDisplayStart: Unit 0: boot screen
Jul 28 09:40:01 [52] CGXMappedDisplayStart: Unit 0: no display alias property
Jul 28 09:40:02 [52] CGXMappedDisplayStart: Unit 1: no display alias property
Jul 28 09:40:10 [52] AGCAttach: Couldn't find any matches
Jul 28 09:40:10 [52] CGXPerformInitialDisplayConfiguration
Jul 28 09:40:10 [52] Display 0x4272800: MappedDisplay Unit 0; Vendor 0x610 Model 0x9ca0 S/N 0; online enabled built-in (0,0)[1280 x 800], base addr 0x1800000
Jul 28 09:40:10 [52] Display 0x3f003d: MappedDisplay Unit 1; Vendor 0xffffffff Model 0xffffffff S/N -1; offline enabled (2304,0)[1 x 1], base addr 0x1800000
Jul 28 09:40:11 [52] kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:40:11 [52] kCGErrorIllegalArgument: Set a breakpoint at CGErrorBreakpoint() to catch errors as they are returned
Jul 28 09:40:11 [52] kCGErrorIllegalArgument: CGXOrderWindow: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:40:10 [52] GLCompositor: GL renderer id 0x0002260e, GL mask 0x00000003, accelerator 0x0000282f, unit 0, caps 0x00000003, vram 256 MB
Jul 28 09:40:10 [52] GLCompositor: GL renderer id 0x0002260e, GL mask 0x00000003, texture units 4, texture max 8192, viewport max {8192, 8192} extensions 0x0000000f
Jul 28 09:41:57 [52] kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:41:57 [52] kCGErrorIllegalArgument: CGXOrderWindow: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:42:34 [53] Server is starting up
Jul 28 09:42:35 [53] CGXMappedDisplayStart: Unit 0: boot screen
Jul 28 09:42:36 [53] CGXMappedDisplayStart: Unit 0: no display alias property
Jul 28 09:42:36 [53] CGXMappedDisplayStart: Unit 1: no display alias property
Jul 28 09:42:36 [53] AGCAttach: Couldn't find any matches
Jul 28 09:42:36 [53] CGXPerformInitialDisplayConfiguration
Jul 28 09:42:36 [53] Display 0x4272800: MappedDisplay Unit 0; Vendor 0x610 Model 0x9ca0 S/N 0; online enabled built-in (0,0)[1280 x 800], base addr 0x1800000
Jul 28 09:42:36 [53] Display 0x3f003d: MappedDisplay Unit 1; Vendor 0xffffffff Model 0xffffffff S/N -1; offline enabled (2304,0)[1 x 1], base addr 0x1800000
Jul 28 09:42:37 [53] kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:42:37 [53] kCGErrorIllegalArgument: Set a breakpoint at CGErrorBreakpoint() to catch errors as they are returned
Jul 28 09:42:37 [53] kCGErrorIllegalArgument: CGXOrderWindow: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:42:38 [53] GLCompositor: GL renderer id 0x0002260e, GL mask 0x00000003, accelerator 0x0000282f, unit 0, caps 0x00000003, vram 256 MB
Jul 28 09:42:38 [53] GLCompositor: GL renderer id 0x0002260e, GL mask 0x00000003, texture units 4, texture max 8192, viewport max {8192, 8192} extensions 0x0000000f
Jul 28 09:43:24 [53] kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:43:24 [53] kCGErrorIllegalArgument: CGXOrderWindow: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:44:16 [53] Server is starting up
Jul 28 09:44:16 [53] CGXMappedDisplayStart: Unit 0: boot screen
Jul 28 09:44:16 [53] CGXMappedDisplayStart: Unit 0: no display alias property
Jul 28 09:44:17 [53] CGXMappedDisplayStart: Unit 1: no display alias property
Jul 28 09:44:17 [53] AGCAttach: Couldn't find any matches
Jul 28 09:44:17 [53] CGXPerformInitialDisplayConfiguration
Jul 28 09:44:17 [53] Display 0x4272800: MappedDisplay Unit 0; Vendor 0x610 Model 0x9ca0 S/N 0; online enabled built-in (0,0)[1280 x 800], base addr 0x1800000
Jul 28 09:44:17 [53] Display 0x3f003d: MappedDisplay Unit 1; Vendor 0xffffffff Model 0xffffffff S/N -1; offline enabled (2304,0)[1 x 1], base addr 0x1800000
Jul 28 09:44:18 [53] kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:44:18 [53] kCGErrorIllegalArgument: Set a breakpoint at CGErrorBreakpoint() to catch errors as they are returned
Jul 28 09:44:18 [53] kCGErrorIllegalArgument: CGXOrderWindow: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:44:19 [53] GLCompositor: GL renderer id 0x0002260e, GL mask 0x00000003, accelerator 0x0000282f, unit 0, caps 0x00000003, vram 256 MB
Jul 28 09:44:19 [53] GLCompositor: GL renderer id 0x0002260e, GL mask 0x00000003, texture units 4, texture max 8192, viewport max {8192, 8192} extensions 0x0000000f
Jul 28 09:45:32 [53] kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:45:32 [53] kCGErrorIllegalArgument: CGXOrderWindow: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:46:16 [53] Server is starting up
Jul 28 09:46:18 [53] CGXMappedDisplayStart: Unit 0: boot screen
Jul 28 09:46:18 [53] CGXMappedDisplayStart: Unit 0: no display alias property
Jul 28 09:46:18 [53] CGXMappedDisplayStart: Unit 1: no display alias property
Jul 28 09:46:18 [53] AGCAttach: Couldn't find any matches
Jul 28 09:46:18 [53] CGXPerformInitialDisplayConfiguration
Jul 28 09:46:18 [53] Display 0x4272800: MappedDisplay Unit 0; Vendor 0x610 Model 0x9ca0 S/N 0; online enabled built-in (0,0)[1280 x 800], base addr 0x1800000
Jul 28 09:46:18 [53] Display 0x3f003d: MappedDisplay Unit 1; Vendor 0xffffffff Model 0xffffffff S/N -1; offline enabled (2304,0)[1 x 1], base addr 0x1800000
Jul 28 09:46:20 [53] kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:46:20 [53] kCGErrorIllegalArgument: Set a breakpoint at CGErrorBreakpoint() to catch errors as they are returned
Jul 28 09:46:20 [53] kCGErrorIllegalArgument: CGXOrderWindow: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:46:20 [53] GLCompositor: GL renderer id 0x0002260e, GL mask 0x00000003, accelerator 0x0000282f, unit 0, caps 0x00000003, vram 256 MB
Jul 28 09:46:20 [53] GLCompositor: GL renderer id 0x0002260e, GL mask 0x00000003, texture units 4, texture max 8192, viewport max {8192, 8192} extensions 0x0000000f
Jul 28 09:46:58 [53] kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:46:58 [53] kCGErrorIllegalArgument: CGXOrderWindow: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:48:03 [53] Server is starting up
Jul 28 09:48:04 [53] CGXMappedDisplayStart: Unit 0: boot screen
Jul 28 09:48:04 [53] CGXMappedDisplayStart: Unit 0: no display alias property
Jul 28 09:48:04 [53] CGXMappedDisplayStart: Unit 1: no display alias property
Jul 28 09:48:04 [53] AGCAttach: Couldn't find any matches
Jul 28 09:48:04 [53] CGXPerformInitialDisplayConfiguration
Jul 28 09:48:04 [53] Display 0x4272800: MappedDisplay Unit 0; Vendor 0x610 Model 0x9ca0 S/N 0; online enabled built-in (0,0)[1280 x 800], base addr 0x1800000
Jul 28 09:48:04 [53] Display 0x3f003d: MappedDisplay Unit 1; Vendor 0xffffffff Model 0xffffffff S/N -1; offline enabled (2304,0)[1 x 1], base addr 0x1800000
Jul 28 09:48:05 [53] kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:48:05 [53] kCGErrorIllegalArgument: Set a breakpoint at CGErrorBreakpoint() to catch errors as they are returned
Jul 28 09:48:05 [53] kCGErrorIllegalArgument: CGXOrderWindow: Operation on a window 0x2 not owned by caller SecurityAgent
Jul 28 09:48:06 [53] GLCompositor: GL renderer id 0x0002260e, GL mask 0x00000003, accelerator 0x0000282f, unit 0, caps 0x00000003, vram 256 MB
Jul 28 09:48:06 [53] GLCompositor: GL renderer id 0x0002260e, GL mask 0x00000003, texture units 4, texture max 8192, viewport max {8192, 8192} extensions 0x0000000f
I had a macbook 3.1 white with external VGA and i never had any issue during 15 months of use (with external screen 5 days per week).

Occasional graphics errors on external monitor

Overall, I'm pretty happy with Lion. Occasionally however, I have video graphics glitches on my MacBook Pro. Sometimes it happens when using an external monitor, sometimes it also happens on the notebook display.
I often get a distorted task switcher:
Also, Safari sometimes renders the content in a weird way, with yellow and red blocks:
And finally, the translucent part of the taskbar sometimes looks funny, with stray pixels running through:
I wanted to mention that it's not a big concern, but when typing the previous version of this message, I detached the external monitor and then all I got was a black screen when opening the lid. I had to power down the MacBook.
Anyone else seen this behaviour?

Replying to my own question...
There's a much longer-running thread (since Nov. 30th, 2011) here, about this issue. Apparently, I'm not the only one.
https://discussions.apple.com/message/16881510#16881510

Screen flickering really bad after unplugging external monitor

Hello,
Since I updated my Macbook Pro 13' Retina (inch, Early 2013) to Mavericks, almost averytime I unplug my external monitor or TV, the screen starts flickering really bad. This is the screenshot of the issue. Sometimes you can see all the apps opens, but the "flicker" effect takes over the screen, making it impossible to user the computer. The only way I found to use the compuer again is restarting it. It's really weird.

Howdy inireugg,
We've an article that provides a host of helpful information and tips for resolving issues with displays.
No video or no signal, image distortion, "snow," or flickering
Check connections
When using an external display be sure to check the following:
If you're using an Apple notebook, confirm the AC power cable or adapter is securely connected to the computer and the cable providing power to the display is also secure. It is always good to have your notebook connected to AC power when an external display is in use.
Confirm display adapters are fully seated in their respective connections and that they are supported models and for the computer and display. Refer to these articles to assist you with adapter compatibility and further configuration information:
Monitor and Display Adapter Table
About Mini DisplayPort to HDMI adapters
Apple Mini DisplayPort adapters: Frequently asked questions (FAQ)
Thunderbolt ports and displays: Frequently asked questions (FAQ)
Remove all display cable extenders, KVM switches, or other like devices and retest to determine if the issue is resolved.
Try unplugging the video adapter or cable and then plug it back in.
If more than one video adapter is in use (or "daisy-chained"), troubleshoot by using only one adapter.
Example: A mini DisplayPort to DVI adapter connected to a DVI to HDMI adapter is an unsupported configuration because there is a series of adapters in use.
If available, try using a different display and or adapter (or use a different connector by using DVI instead of VGA, for instance).
Reset the systemYou can reset the Mac's parameter RAM and SMC.Reset the resolutionStart by resetting the Mac's parameter RAM. If the display does not come up, was previously set to an unsupported resolution, and still results in no video:
Start up in Safe Mode.
From the Apple () menu, choose System Preferences.
Choose Displays from the View menu to open the preferences pane.
Select any resolution and refresh rate that your display supports.
Restart your computer.
Apple computers: Troubleshooting issues with video on internal or external displays
http://support.apple.com/kb/HT1573
Cheers,
Allen

External monitor flickering issues on T520

Hi, I have a Lenovo T520 with Nvidia NVS 4200M with the latest driver installed. I pluged both a VGA external monitor, then removed it and pluged a newer Displayport monitor and both monitors flicker. Thank youFrançois

Yes they are all on recommended resolutions. I did a factory reset on my Dell Ultrasharp monitor (with mini-displayport to displayport cable) but it did the same flickering on an older HP LCD display with VGA connexion. I'm going to try changing the vsync settings. It is on "use the 3D application setting" now but I will try "adaptive". And I also noticed there is a newer Nvidia driver from windows update, I will try that after. Thank you!Frankie

My external monitor flickers intermittently and wont function when connected to macbook pro

Hello everyone,
I recently purchased a cable to convert the thunderbolt/miniport to the VGA input on an external monitor I have had laying around for a few years. I am currently running osx 10.7.5 on a macbook pro.
When I plugged the cable to connect my macbook to the monitor, the monitor certainly recognized the cable, but the display would not do more than flicker in and out intermittently when connected to my macbook.
I have searched the forums for a solution to this, but haven't been able to find one that works. I tried resetting the SMC and restarting while holding cmd+P+R but none of these "fixes" seemed to help.

Simplest thing to try is a PRAM reset.
Shut down your Mac.
Locate the following keys on the keyboard: Command (⌘), Option, P, and R. You will need to hold these keys down simultaneously in step 4.
Turn on the computer.
Press and hold the Command-Option-P-R keys before the gray screen appears.
Hold the keys down until the computer restarts and you hear the startup sound for the second time.
Release the keys.
Excerpt from http://support.apple.com/kb/ht1379

PB display flickers, but external monitor still OK

Hi all,
I've just bought a faulty powerbook to see if i can fix it. It's a G4 15" 1Ghz Titanium DVI. The fault is that the powerbook display frequently becomes corrupted. it's actually a beautiful effect, but not very practical! Every few moments, minutes sometimes, the display looks as if deep colours are gradualy bleeding accross it, until it becomes unreadable. the effect is sometimes psycedelic and sometimes textured like oil on canvas!
Anyway, simply moving the angle of the display a little clears the screen and everything's visible again. At no time does the system crash or anything; if there's an external monitor conected in Display Mirroring or Extended Desktop mode it doesn't show any artifacts and continues to work perfectly. It's only the powerbook's own display that exhibits the fault.
i'm presuming therefore that the logic board is OK but that there is a loose connection somewhere (where I don't know!). Could it be the invertor board however?
does this all sound familiar to anyone?
thanks!
TiBook 1Ghz (DVI) Mac OS X (10.3.9) 9600/350

Hi, efunc. If your situation is such that you could happily use the Powerbook as a very compact desktop computer with its built-in display closed and an external monitor, keyboard and mouse connected, you might be able to do so for a long time without fixing anything at all.
If you really want to use the Powerbook as a portable, you'll have to crawl inside and look around for the trouble. The fact that changing the built-in display's angle clears the problem suggests strongly that the cause is in one of the very thin, fragile cables that pass through the display hinges. These can become pinched or abraded in the very narrow passageway there (especially if the hinges are fatigued and begining to break), leading to faulty insulation and short circuits or even severed cables. There is very little room there to make any repairs, if that's the case, and cable damage is not always easy to see. Replacing the cables, one end of which is sealed inside the display bezel, is essentially impossible. A professional technician, when faced with bad display cables, replaces the entire display instead of trying to pry the bezel apart.
Because the cables are so thin, flexible and delicate, the motion of the display being opened, closed and adjusted is, in itself, very unlikely to loosen (or tighten) any of the cables' connections inside the body of the Powerbook. But a loose connection there is possible, and it wouldn't hurt to check. Complete disassembly instructions are here, and will show you where the display cable connections are located.
If you don't find a bad connection, the inverter board is the least expensive part you could replace in the hope of solving the problem. But I doubt that adjusting the screen angle would "fix" (even temporarily) a problem caused by a bad inverter, so I suspect that isn't where the fault lies.
Good luck.
EDIT: Oh, dear — I just realized that you're the very same efunc who reports a whole different set of problems with his used 1GHz Tibook in a different thread. If all those problems are occurring in the same Tibook as the display problems discussed in this thread, most of what I've said above is out the window, and the source of all the problems could be anywhere, including the logic board, or even multiple sources.
My comments above were based on the assumption that the problem you reported in this thread was the only one you were having with the affected machine. If that assumption is wrong, disregard them.

External monitor not working after ML upgrade

I have a late 2008 Unibody Macbook and normally use it in clamshell mode with a Samsung 2043NW monitor if I'm in the office. Previously working fine in 10.5.8 through mini display port adapter. Upgraded via fresh install of 10.6.8 to ML, and the monitor flickered on occasionally but otherwise would not work - when it did display it showed the same resolution as the macbook screen i.e. 1280 X 800 instead of 1680 X 1050.
There's a thread here related to this: https://discussions.apple.com/thread/2387462?start=15&tstart=0 but this software was not the answer. I can now view the screen, but it is still being sent a resolution of 1280X800, rather than 1680X1050 (i.e. a fuzzy mess). It also will not work in clamshell mode at all, and just goes to sleep when the case is shut.
Anyone have a solution for this, or have I been 'obsolesced'? Does anyone have a unibody Macbook that DOES work with an external monitor?

OK, now here's an interesting thing - the macbook has begun to work in clamshell mode. This is REALLY weird. Tried again this morning in the hope of getting back the monitor control icon in the toolbar and it booted straight into clamshell mode with the lid shut.
When I first had this running 10.5 it would only work in clamshell mode if you pressed the power button and immediately closed the lid before the screen lit up grey. More recently it has been perfectly happy to enter clamshell mode after a period of use normally, just plugging in the monitor and shutting the lid. It would be nice if this behaviour were to start again soon.

Problem with T61 and DVI External Monitor (via Advanced Mini-Dock)

Ever since I upgraded to Vista SP1 on my ThinkPad T61 (with an Intel integrated 965 series graphics card), I've been having problems when I try to use an external monitor via the DVI port in my Advanced Mini-dock. I'm curious if other people have experienced this problem.
The problems surfaces when I first boot up, or sometimes after my ThinkPad has been running for awhile (particularly when I do something graphics related, such as right-clicking to open display properties). The picture starts to flicker (or disappear and reappear, like the screen does when changing graphics resolutions). I also hear the "ba-bum" sound that you hear when disconnecting a piece of hardware, followed by the "bum-ba" reconnection sound - these two sounds happen repeatedly (sometimes as fast as once per second). If I don't do anything, sometimes I'll get a bluescreen.
Not long ago, I found a fix of sorts: to stop the flickering/reconnecting, I just open Task Manager and stop the process called "igfxpers" (an Intel driver problem). The problem always disappears after I do this, although I have to remember to do it every time I reboot or else the problem comes back. So it's not an ideal fix.
This problem doesn't happen when I connect an external monitor using the analog VGA port, or when I'm just using the notebook LCD. It's limited to just the DVI connection. I've tried two different digital monitors (one LG, the other BenQ) as well as two DVI cables - the problem is still the same. So it seems like a driver problem of some sort - unfortunately, the Intel drivers haven't been updated since last February.
I should also note that I've tried reinstalling my OS two or three times, and the problem always comes back. Has anyone else had this problem, and is a fix on the way?

Error Message:
Input signal out of range. Translation:
You will see this on an otherwise blank screen. Assuming that the data cable is plugged in correctly, the video card is feeding the monitor a signal stream in excess of what the monitor can accommodate. The two main causes for this are that the user has set either the resolution or the vertical frequency rate too high. For example, you might set a new graphics card to display at 1,280 x 1,024, but if the monitor is only capable of 1,024 x 768 resolution, you’ll get a Sync Out of Range error. This is especially common in 14-inch monitors.
Solution:
Because you obviously can’t make settings changes from within regular Windows, you’ll need to reboot into Windows Safe Mode. When you restart the system, there is a point during boot up when the system switches from reporting diagnostics and detected components to loading Windows. This point is usually accompanied by a beep and the screen going black. Just before this point, you want to start repeatedly pressing the F8 key. This should bring up a menu of Windows boot options. The one you want to pick is Safe Mode.
From Safe Mode right-click the Desktop and select Properties. Go to the Settings tab and use the slider to drop your resolution a notch or two. Reboot and let Windows try to go into Normal mode. If this still doesn’t work, go back into Safe Mode and get to the Settings tab of Display Properties. Click the Advanced button, go to the Monitor tab, and check your refresh rate. The lowest advisable rate is usually 60Hz, although this works better for LCDs (liquid-crystal displays) than CRTs (cathode ray tubes). Apply the change and reboot.

External monitor occasionally flickers

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