27" Late 2009 i5 iMac - does it have Intel HD Graphics?

[jonnymorris]

My old iMac is currently sitting in storage with a borked GPU, I baked it once and that worked for a few months, don't want to do it again. I have a friend who might be able to do a proper reball but he doesn't have the time at the moment (and probably won't for a while), and I don't feel it's worth paying a professional to do it, so there it sits.

I recently had a similar problem with the discreet GPU in my 2011 MacBook Pro, which is currently my main computer for emails etc, and I found guides on how to disable the discreet GPU in NVRAM or somesuch to force it to use the onboard Intel graphics, lots of address poking that I don't have the faintest hope of trying to replicate on my own for the iMac. So I'm wondering if anyone knows if the 27" iMac from Late 2009 has that same Intel graphics option, and if the iMac could be permanently poked to use it instead of the AMD graphics card. It manages to work in Safe Mode so it's obviously able to tap into something to drive that big screen, though I recall it was rather slow.

 

[Navigator98]

Hey, I happen to have the very same iMac with a dead GPU. Best you can do apart from reballing or replacing the GPU is preventing it from loading graphic kexts (drivers) and disabling as many animations as you can, as the system will be running without graphics acceleration from then on. Many third party apps won't work or be very slow, but all built-in apps do and so does the sound & target display mode (so you could still use it as an external display if you wanted to). One caveat is that brightness adjustments do not seem to work, but for the rest it's quite usable for normal office work.

To disable your graphics kexts do as follows:

1. Reboot to recovery (Cmd+R)
2. Open Terminal window - type csrutil disable - this disables System Integrity protection which is required to modify the kext files.
3. Reboot to safe mode (hold shift when the computer is booting)
4. Open Terminal window - type
   1. sudo /sbin/mount -uw /
   2. mkdir /DisabledSys
   3. cd /System/Library/Extensions
   4. sudo mv AMD4* /DisabledSys (this is assuming you also have an ATI/AMD HD4850 or HD4670)
   5. Repair the kext permissions and rebuilt the cache - enter one command at a time and press enter:
      
      sudo chmod -Rf 755 /S*/L*/E*
      sudo chmod -Rf 755 /L*/E*
      sudo chown -Rf 0:0 /S*/L*/E*
      sudo chown -Rf 0:0 /L*/E*
      sudo kextcache -i /
5. Reboot (normal, no safe mode - system should boot without graphics acceleration and sound will work)
6. Disable all possible animations to speed things up and reboot one more time after this:

defaults write -g NSAutomaticWindowAnimationsEnabled -bool false
defaults write -g NSScrollAnimationEnabled -bool false
defaults write -g NSWindowResizeTime -float 0.001
defaults write -g QLPanelAnimationDuration -float 0
defaults write -g NSScrollViewRubberbanding -bool false
defaults write -g NSDocumentRevisionsWindowTransformAnimation -bool false
defaults write -g NSToolbarFullScreenAnimationDuration -float 0
defaults write -g NSBrowserColumnAnimationSpeedMultiplier -float 0
defaults write com.apple.dock autohide-time-modifier -float 0
defaults write com.apple.dock autohide-delay -float 0
defaults write com.apple.dock expose-animation-duration -float 0
defaults write com.apple.dock springboard-show-duration -float 0
defaults write com.apple.dock springboard-hide-duration -float 0
defaults write com.apple.dock springboard-page-duration -float 0
defaults write com.apple.finder DisableAllAnimations -bool true
defaults write com.apple.Mail DisableSendAnimations -bool true
defaults write com.apple.Mail DisableReplyAnimations -bool true

Additionally, toggle the following in System Preferences:

• LCD Font Smoothing off
• Always show scroll bars
• Reduce transparency ON
• Reduce motion ON

Hope this helps! If you ever wish to restore the graphics kexts just move them back from the DisabledSys folder via Terminal in recovery mode. I would also recommend you re-enable System Integrity Protection by entering csrutil enable in Terminal while you are in recovery mode, but this is optional (although strongly recommended for security purposes).

Best of luck!

 

[jonnymorris]

Hey, thanks very much for that info, I thought there would be some way of using the system without the AMD GPU.

I used to use the iMac a lot in Target Display mode (something which, when asked, pretty much every Mac reseller denied all knowledge of when I enquired if newer models had this) but noticed that the iMac ran quite hot while doing so, probably more than in general use... something in there still wanted to drive the display in a less than efficient manner - my current 27" monitor doesn't get so hot, so why should an iMac when it's just in theory acting as a through-put? I blame Apple! I'm wondering if using the iMac in this manner is what contributed to the GPU dieing, impossible to know for sure I suppose, but like with the Superdrive it was probably destined to fail regardless (I hardly ever used the Superdrive and it still failed).

 

[Nguyen Duc Hieu]

I also got another iMac 2009 with a halff-dead HD4850m
I got it baked at a laptop repair shop, but it wasn't fixed.
I bought a Quadro K1100m (retrieved from a Dell laptop), flashed it with a modified VBIOS.
And now I could use my iMac 2009 again with the new GPU.
The only issue is: Backlight level is not changeable and the LCD is hot (65 degrees Celsius). It stayed fully bright.
If I apply the fix (Kext injection, etc) the LCD lost 30% of its brightness (at max controllable level).

 

[jonnymorris]

I also got another iMac 2009 with a halff-dead HD4850m
I got it baked at a laptop repair shop, but it wasn't fixed.
I bought a Quadro K1100m (retrieved from a Dell laptop), flashed it with a modified VBIOS.
And now I could use my iMac 2009 again with the new GPU.
The only issue is: Backlight level is not changeable and the LCD is hot (65 degrees Celsius). It stayed fully bright.
If I apply the fix (Kext injection, etc) the LCD lost 30% of its brightness (at max controllable level).

View attachment 1783969

Interesting to hear about these laptop GPUs that can be made to work, or mostly work.

I couldn't live with that kind of brightness though, I would always run mine on the minimum (maybe only a couple of notches above 'black'), same for my MacBook Pro, anything brighter just tends to hurt my eyes and feels unnecessary. I suppose the heat is due to the brightness, that would surely shorten the life of the display.

 

[Nguyen Duc Hieu]

Interesting to hear about these laptop GPUs that can be made to work, or mostly work.

I couldn't live with that kind of brightness though, I would always run mine on the minimum (maybe only a couple of notches above 'black'), same for my MacBook Pro, anything brighter just tends to hurt my eyes and feels unnecessary. I suppose the heat is due to the brightness, that would surely shorten the life of the display.

In your case, you will be happy with the simple fix. The expert has made a disk image with all the necessary fix on it. Just donwload it, restore to an SD card of a USB stick, and make it a default boot device.
The maximum backlight level will be reduced to 50˜70% of unfixed one, and you can lower it to minimum, which is barely visible.

If you are interested in reviving your GPU-dead iMac, welcome to the club below.

2011 iMac Graphics Card Upgrade

iMac 2009 to 2011 MXM3 graphics card upgrade (Lastest update 10/13/2023 - this is the official documentation page - you found it finally!) This is the single and only documentation post. During the last years we constantly updated this post to reflect the lastet development of vBIOS and OCLP...

forums.macrumors.com

 

[Nguyen Duc Hieu]

To be updated:
I've just applied a new fix that clear out all of the backlight issues.
My iMac late 2009 is now working perfectly in High Sierra.
And I can upgrade the OS to Catalina or Big Sur whenever I like.