27 inch iMac won't boot normally (screen flickers)

My old iMac (early 2009, 27 inch, 3.06 core 2 Duo, 4 GB 800 MHz DDR2 SDRAM) had, and continues to have a problem with the display. When attempting a normal boot, a minute or so after the Apple logo appears, the display goes black except for the top 10 or 20%, which rapidly flickers. I've run Disk Utility to verify the permissions and verify the disk and those appear okay. Also, ran the Apple Hardware Test from the install DVD and that appears okay, also. I've reinstalled Mountain Lion (a couple of times) hoping that maybe, somehow, it might surprise me but, still disappointed...
The easiest, least invasive thing I've done has been to just reseat the two memory sticks. Didn't hurt, but didn't help, either.
It's able to boot in Safe Mode, which I've been doing for quite a long while now, but it would be nice to have everything functioning normally again. Other than opening the iMac up to have a look inside, is there any other test(s) that can be done to get a better idea of what the problem might actually be?
Thanks.

It restarts okay and does what it's able to in Safe Mode. That's what I've been doing for a while, now.
Sure would be nice to have a fully functioning iMac again, though.
AppleCare is way in the past at this point. One of these days, I'll take it to an Apple Store and let them have a go at it. Or, at least give me the (bad) news as to how much it'll cost.
If it should turn out to be the graphics unit (been reading less than complimentary things about Nvidia 8800 gs), any estimate on what Apple might charge for that sort of repair? If not, no worries. Guess I'll find out soon enough.
Thanks...

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Imac won't boot - white screen

Ok, so now my imac won't boot. All I get is a white screen; I also can't boot from install DVD.

Hi David
Try booting the Install DVD holding the Option key or run the Apple Hardware Test as described in the following Apple article > http://support.apple.com/kb/HT1509
Dennis

IMac won't boot, dark screen after normal grey start up screen

Quite perplexed with this problem, have tried everything I can think of.
Computer: iMac 2.16 gHz 24" mid 2006, 4 gig RAM
OS: 10.6.8
Froze and required hard shutdown. Subsequent to this, has behaved consistently:
Normal grey screen with Apple logo and spinning timer, can hear disk activity. Then the screen goes dark and nothing else happens (although the computer is still on). Have to perform hard shutdown.
Have tried:
1. Booting into single user mode (multiple times) and performed fsck, no errors noted
2. after using 'exit' command in single user mode, computer attempts to reboot but then freezes after noting 'panic'
3. Reset PRAM (no change)
4. Tried safe mode boot, progress bar on grey screen progresses, then spinning timers comes on, then same crash with dark screen
4. Disassembled computer, removed hard drive, mounted normally in external SATA enclosure. I backed up critical data, ran Disk Utility Repair, no errors noted.
5. Reinstalled HD, reassembled computer, rebooted, same issue
6. Attmepted to boot with Snow Leopard Install disc to perform a fresh Achive and Install - after prolonged grey screen with spinning timer and audible DVD drive access, same switch to dark screen and no further progress
7. Same panic message and stalled boot attempt noted when booting into single user mod
I'm stumped. My assumption is that there is a courrpt file that is causing a kernel panic during boot and I assumed that I'd be able to perform an archive and install but when this failed I'm guessing all I can do is replace the hard drive with a new one and then go through the hassle of transferring all the data over manually.
I would welcome hearing any other observations, similar experiences or other ideas. MTIA.

One update ... when I boot the computer and get the 'dark screen', I hear disc activity. So I started hitting the return key and I get the chime with each return as if I'm on the log in screen and hitting the return to log in without entering any text.
That would argue there is a problem with the screen.
However, it does not explain why the computer display works normally during single user mode and hangs (without the screen going dark) when trying to reboot from this mode.

Imac won't boot (grey screen, prohibit sign, folder with ? mark)

Before I bring my iMac to a store (which I can barely lift on my own!), I thought I'd give one last shot in the forums. I've already spoken with Apple Care who, after two rounds of phone support, said it's time to bring it in.
My computer was working fine but I had to force quit a few programs. Finally I had to shut it down, and when trying to reboot, I get stuck on the grey screen with the progress wheel spinning. I tried holding the C button, used the Install disc to try "Disk Utility". What came up with Disk Utility was it said it was rebuilding a B-tree, and then just hung. I tried that again (all with Apple Care on the phone) and then it couldn't find the hard drive.
So... any other ideas? Let me know if you need more information; I am desperate for help before I have to find a babysitter for my child so I can get this computer out the door for some (gasp!) data recovery!

Ouch....Time machine would mean moving on to 10.5...
If you decide to stay with 10.4 may I recommend SuperDuper! for cloning/backing up...30 bucks and easy to use....
I run 3 different external drives 2 for clones of my system and one for storage of various folders...cuts down on worries
Again I also suggest going with one or both of the Utilities I mentioned when the time is right....
Personally I don't have anything on my Mac's that is worth $1200....don't hold your breath on Apple doing anything about your Mac's ultimate demise
dave

My iMac won't boot past grey screen and it didn't come with a os x disk

My iMac won't boot past grey screen with apple. I've tried booting in safemode but that didn't help and my iMac didn't come with a os x disk.

Take each of these steps that you haven't already tried. Stop when the problem is resolved.
Step 1
The first step in dealing with a startup failure is to secure the data. If you want to preserve the contents of the startup drive, and you don't already have at least one current backup, you must try to back up now, before you do anything else. It may or may not be possible. If you don't care about the data that has changed since the last backup, you can skip this step.
There are several ways to back up a Mac that is unable to start. You need an external hard drive to hold the backup data.
a. Start up from the Recovery partition, or from a local Time Machine backup volume (option key at startup.) When the OS X Utilities screen appears, launch Disk Utility and follow the instructions in this support article, under “Instructions for backing up to an external hard disk via Disk Utility.”
b. If you have access to a working Mac, and both it and the non-working Mac have FireWire or Thunderbolt ports, start the non-working Mac in target disk mode. Use the working Mac to copy the data to another drive. This technique won't work with USB, Ethernet, Wi-Fi, or Bluetooth.
c. If the internal drive of the non-working Mac is user-replaceable, remove it and mount it in an external enclosure or drive dock. Use another Mac to copy the data.
Step 2
If the startup process stops at a blank gray screen with no Apple logo or spinning "daisy wheel," then the startup volume may be full. If you had previously seen warnings of low disk space, this is almost certainly the case. You might be able to start up in safe mode even though you can't start up normally. Otherwise, start up from an external drive, or else use either of the techniques in Steps 1b and 1c to mount the internal drive and delete some files. According to Apple documentation, you need at least 9 GB of available space on the startup volume (as shown in the Finder Info window) for normal operation.
Step 3
Sometimes a startup failure can be resolved by resetting the NVRAM.
Step 4
If you use a wireless keyboard, trackpad, or mouse, replace or recharge the batteries. The battery level shown in the Bluetooth menu item may not be accurate.
Step 5
If there's a built-in optical drive, a disc may be stuck in it. Follow these instructions to eject it.
Step 6
Press and hold the power button until the power shuts off. Disconnect all wired peripherals except those needed to start up, and remove all aftermarket expansion cards. Use a different keyboard and/or mouse, if those devices are wired. If you can start up now, one of the devices you disconnected, or a combination of them, is causing the problem. Finding out which one is a process of elimination.
Step 7
If you've started from an external storage device, make sure that the internal startup volume is selected in the Startup Disk pane of System Preferences.
Start up in safe mode. Note: If FileVault is enabled, or if a firmware password is set, or if the startup volume is a Fusion Drive or a software RAID, you can’t do this. Post for further instructions.
Safe mode is much slower to start and run than normal, and some things won’t work at all, including wireless networking on certain Macs.
The login screen appears even if you usually log in automatically. You must know the login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
When you start up in safe mode, it's normal to see a dark gray progress bar on a light gray background. If the progress bar gets stuck for more than a few minutes, or if the system shuts down automatically while the progress bar is displayed, the startup volume is corrupt and the drive is probably malfunctioning. In that case, go to Step 10. If you ever have another problem with the drive, replace it immediately.
If you can start and log in in safe mode, empty the Trash, and then open the Finder Info window on the startup volume ("Macintosh HD," unless you gave it a different name.) Check that you have at least 9 GB of available space, as shown in the window. If you don't, copy as many files as necessary to another volume (not another folder on the same volume) and delete the originals. Deletion isn't complete until you empty the Trash again. Do this until the available space is more than 9 GB. Then restart as usual (i.e., not in safe mode.)
If the startup process hangs again, the problem is likely caused by a third-party system modification that you installed. Post for further instructions.
Step 8
Launch Disk Utility in Recovery mode (see Step 1.) Select the startup volume, then run Repair Disk. If any problems are found, repeat until clear. If Disk Utility reports that the volume can't be repaired, the drive has malfunctioned and should be replaced. You might choose to tolerate one such malfunction in the life of the drive. In that case, erase the volume and restore from a backup. If the same thing ever happens again, replace the drive immediately.
This is one of the rare situations in which you should also run Repair Permissions, ignoring the false warnings it may produce. Look for the line "Permissions repair complete" at the end of the output. Then restart as usual.
Step 9
Reinstall the OS. If the Mac was upgraded from an older version of OS X, you’ll need the Apple ID and password you used to upgrade.
Step 10
Do as in Step 9, but this time erase the startup volume in Disk Utility before installing. The system should automatically restart into the Setup Assistant. Follow the prompts to transfer the data from a Time Machine or other backup.
Step 11
This step applies only to models that have a logic-board ("PRAM") battery: all Mac Pro's and some others (not current models.) Both desktop and portable Macs used to have such a battery. The logic-board battery, if there is one, is separate from the main battery of a portable. A dead logic-board battery can cause a startup failure. Typically the failure will be preceded by loss of the settings for the startup disk and system clock. See the user manual for replacement instructions. You may have to take the machine to a service provider to have the battery replaced.
Step 12
If you get this far, you're probably dealing with a hardware fault. Make a "Genius" appointment at an Apple Store, or go to another authorized service provider.

My iMac won't boot. I only get a white screen. Won't open in safe mode or recovery mode. Any suggestions?

Hey, any help? My 24" iMac won't boot. I only get a white screen when turning on. It won't open in safe or recovery mode. Any suggestions?

If you can't boot from your installer DVD, then take it in for service.

My imac won't boot up. I get a white screen with the apple logo and the spinning spiral--any ideas?

my imac won't boot up. I get a white screen with the apple logo and the spinning spiral--any ideas?
I have started having trouble since i had to upgrade OS the latest in July 12.

http://support.apple.com/kb/TS2570 Follow this article and when it gets to the part where you go into disk utility using your install disc, you'll actually boot up holding down Command and R

My iMac won't boot up past the white screen with a grey apple and spinning icon

My iMac won't boot up past the white screen with a grey apple and spinning icon...please help!

command R did not result in anything different - still the white screen, etc. I do you Time Machine with and external hard drive, but I unplugged that. I have the installation DVD, but it doesn't seem to be reading it either.

My iMac won't boot up it has a gray screen and makes a steady beeping sound

My iMac won't boot up it makes a steady beeping sound and has a gray screen, occasionally it shows a picture of a file with a question mark blinking in the center, can anyone help

The blinking question mark indicates that the firmware could not find a valid Operating System on your machine.
Your harddrive may have failed. Your filesystem may have bcome corrupted.

My iMac won't boot up fully. It stays stuck in the gray screen with the pinwheel spinning, then after about 5 minutes just shuts itself off.

My iMac won't boot up fully. It stays stuck in the gray screen with the pinwheel spinning, then after about 5 minutes just shuts itself off.

Try SMC Reset (unplug it from the back of the computer for 10 seconds then plug it back. in)
Try PRAM Reset Cmd + OPtion + P + R on start up.
Try safe boot - hold down shift on start up.
Try booting to install dvd (C on start up) or recovery hd (CMD + R) and using disk utility to run a verify and repair. If you still can't boot after that reinstall the operating system. If you can't find the disc or it wont boot to the disc.
Try single mode which is cmd+S on start up. It will open with a terminal looking window in the terminal. type in /sbin/fsck -TL. If it returns *system has been modified* continue to type that command in until it comes back with macintosh hd seems to be ok. If after 5 tries it still gives you system has been modified. You may have to replace the hard drive.

HT3964 my iMac won't boot up. I hear the chime and the Apple symbol appears but there is no whirling indicator that appears and after a while the computer screen goes black and the whole cycle starts again. There have been occasions when it has actually s

my iMac won't boot up. I hear the chime and the Apple symbol appears but there is no whirling indicator that appears and after a while the computer screen goes black and the whole cycle starts again. There have been occasions when it has actually started and I have the dashboard appear but then the screen freezes

Since you have Lion v10.7.4 installed, use Lion Recovery to repair the startup disk if necessary, or reinstall the Mac OS X.

IMac won't boot after power outage

I got a power outage a couple of hours ago. And now my iMac won't boot. When I power it up, it gets pass the white screen with the apple logo. The screen than turns blue with a spinning cursor. The cursor spins for about 10-15 minutes and stops but the normal login screen never appear and it won't boot into the desktop either. I just got a blue screen.
I have boot into the install Disc1 and did the disk repair and premission repair but it didn't help.
Any idea?
Sidney

Oh man, what a disaster!
I tried to do an Archive and Install but the installation hanged at the end of disc 2 after running an iWeb script (according to the install log) with about one minute left. I have waited for two hours but it just hanged there with all the drives spin down.
To make the problem worse. There was no way to quit the install at that point because all the menu items were disabled. The only way out was to power off. But when I powered it back on, it booted right into install directly asking for the disc 2. If I put the disc in it will install again and hang at the same spot.
Disc 2 contains iLife. I know Apple wanted to make things simple but why can't they give me an option to skip it? After all, iLife was already installed.
I finally got it working by booting from disc 1 and did a clean install. It took me all night to re-download all the updates and reinstall many applications. Fortunately, I have my address book, calendar, and most of my works backed up to .Mac so it wasn't a total lost.
On the bright side. Now my iMac is working better than before. I used to have problem getting auto sleep to work but now it works perfectly. Safari also had problem accessing charts (but Camino was fine) in a few web sites like schwab.com. Now everything works.
Lenn and David. Thanks for all your helps.
Now I am looking for a better backup solution so that the recovery won't be this painful if disaster strikes again. Any suggestions?
Sidney

27" iMac won't boot from anything BUT the main drive

Hi all,
My lovely 27" iMac is in perfect working condition, but I thought I'd try to install a OS on a large SD card to see if I would gain any speed.
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If I try to hold down the option key during startup, the iMac WILL let me choose which OS to boot from, but if I choose anything else than the OS already installed it freezes.
I've even tried to boot my Mac Pro from the iMac install DVD - no problems.
I've even run a hardware test on the iMac - no problems.
I am running out of options fast! Please help a devoted Mac-friend.
Take care.
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I WAS using the DVD that came with the machine, but I fear Apple may have sent me the wrong one?
In trying to solve the issues I'd tried other OS disc's (A Mac Pro install DVD and a OS X Leopard DVD) - but none of them would even boot, nor install of my iMac. I always end up with a white screen during boot up.
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IMAC won't boot with USB card reader attached

My quite new 24" iMAC won't boot if I have a USB card reader attached:
I get to the white screen with the apple logo, but it gets stuck there and the little spinning gear below the apple logo never appears (I've waited several minutes). (In all my test cases, there is no card in the card reader.)
I've tried two different card readers with the same results ("iDOTconnect" brand and a brand new Apacer unit, both are USB2.0 multi-format card readers).
The 1st one I tried via a USB hub, the second one I tried via a new hub and also directly connected to the mac (both of those hubs work fine).
Anyone have any ideas?
Regards,
Strathglass
Message was edited by: strathglass

Hello strathglass
The same thing can also happen with other connected devices such as external HD's and iPods, the Startup Manager is lost and searching for a boot volume.
1. You may be able to fix it by going to: *System Preference / Startup Disk* and select the *Mac OS X 10.5.5 on Macintosh HD* then *Click the lock to prevent further changes.*
2. Leave those devices that cause boot issues disconnected until the iMac is up and running!
3. Only sleep the iMac, and be sure to disconnect those devices be for shutting down or updates that require a restart!
As a habit, I have always ejected and disconnected all mounted USB devices (flash driver, iPods, cameras, card reader, etc.) from my hub be for sleeping, restarting or shutting down...
Dennis

My iMac won't boot i get an apple logo

my iMac won't boot i get an apple logo

Hi Paul,
If your iMac won't boot past a grey Apple screen, you may find the following article helpful:
Mac OS X: Gray screen appears during startup
http://support.apple.com/kb/ts2570
Regards,
- Brenden

27 inch iMac won't boot normally (screen flickers)

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