Introduction

When the VRAM on my early-2009 24" iMac went bad, I feared I might need to trash the machine. Some sources suggested the video card was soldered to the logic board but that may only be true of the base-model iMac. The ones with the nVidia and ATI upgrades are repairable/upgradable as illustrated in this guide.

This guide will illustrate disconnecting all cables from the logic board, removing all retaining screws from the logic board, removing the logic board, and replacing the video card.

Begin by following the excellent existing guide on opening this model of iMac, thanks to Brittany, located  here. STOP at step 11 of her guide, "Lift and remove the display panel." You do not need to remove the HD to replace/upgrade the video card.
  • Begin by following the excellent existing guide on opening this model of iMac, thanks to Brittany, located here.

    • STOP at step 11 of her guide, "Lift and remove the display panel." You do not need to remove the HD to replace/upgrade the video card.

  • As Illustrated here, I chose a less-expensive alternative to the $15 suction cups to lift the glass. For less than $5 I got a pair of 3M "Command" adhesive coat hangars. They proved more than strong enough. The easy release feature came off cleanly with zero residue.

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Once you've removed the LCD display from the device you can see what you're in for.
  • Once you've removed the LCD display from the device you can see what you're in for.

  • The logic board is outlined here in red. We have to remove it completely since the video card is installed on the backside. Before we do that, we have to carefully separate 17 connectors.

    • You can see parts of the graphics card highlighted in orange. The GPU is on the right and the dedicated heat fins are on the left, located just "downwind" of the CPU heat fins.

  • AFTER we disconnect all the wires, you need to also remove the right speaker enclosure since it covers the corner of the logic board. It's retained with one obvious screw.

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This position on the logic board has three closely-spaced connectors for the power button, ambient temp sensor, and the CPU fan. Unplug them. Disconnect these three connectors for the HD temp sensor, optical drive temp sensor, and hard drive fan. Each one of these three connectors has a different number of pins so you can't mix them up when reconnecting. Thanks, Apple!
  • This position on the logic board has three closely-spaced connectors for the power button, ambient temp sensor, and the CPU fan. Unplug them.

  • Disconnect these three connectors for the HD temp sensor, optical drive temp sensor, and hard drive fan.

    • Each one of these three connectors has a different number of pins so you can't mix them up when reconnecting. Thanks, Apple!

I followed your indications with great success to revive my old iMac 24" (early 2008) by baking its burned-out Nvidia 8800GS !

This is a great step-by-step guide. Thank you very much for publishing it ! I'd like to add some commentaries : the 3 connectors (red point) are rather hard to unplug. Don't loose patience ! You have to pull them slowly with your nails and tweezers to avoid damaging the tiny wires. Don't be afraid, just take your time, because as indicated perfectly by Jeff, each connector has a different size.

Alexandre Lourdel - Reply

Disconnect the plug for the optical drive fan. You have four plugs to disconnect at this location: SATA bus, microphone, and the left and right speaker cables. You have four plugs to disconnect at this location: SATA bus, microphone, and the left and right speaker cables.
  • Disconnect the plug for the optical drive fan.

  • You have four plugs to disconnect at this location: SATA bus, microphone, and the left and right speaker cables.

RED: On my iMac 24" (early 2008), the plug for the optical drive fan is located just on the right side of the SATA bus plug. I'd like to publish a picture of it but I don't know if it's possible here.

ORANGE: On my iMac 24" (early 2008), the SATA plug is tighten by two little screws of the same size than those of the screen data plug. They are easy to remove. All the connectors are different so that it's impossible to mix them up. As said before, some of them could be a bit hard to remove but take your time, they will loosen.

Alexandre Lourdel - Reply

Take a note here how the cable for the left audio speaker (I'm pinching it) is routed loosely above the RAM slots. After you reinstall the logic board, you need to put this back in a similar style.
  • Take a note here how the cable for the left audio speaker (I'm pinching it) is routed loosely above the RAM slots. After you reinstall the logic board, you need to put this back in a similar style.

On my iMac 24" (early 2008), this cable and the power supply one are covered by a plastic fin that you'll have to bend a little to extract the two cables underneath (left speaker and power supply).

Alexandre Lourdel - Reply

Almost there! Time to really go wireless by disconnecting the three WiFi and bluetooth antennas. These are tiny snaps so pull gently upward. Also, sneaking in from underneath, you'll find the iSight camera cable. Unplug it. This is one to look out for when you reinstall the logic board. At last you'll disconnect the main power cord and the Hard Drive SATA cable. I photographed the top one already disconnected; be sure to squeeze the edge tabs to release the clamp hooks. The HDD SATA connector has a convenient pull tab. At last you'll disconnect the main power cord and the Hard Drive SATA cable. I photographed the top one already disconnected; be sure to squeeze the edge tabs to release the clamp hooks. The HDD SATA connector has a convenient pull tab.
  • Almost there! Time to really go wireless by disconnecting the three WiFi and bluetooth antennas. These are tiny snaps so pull gently upward. Also, sneaking in from underneath, you'll find the iSight camera cable. Unplug it. This is one to look out for when you reinstall the logic board.

  • At last you'll disconnect the main power cord and the Hard Drive SATA cable. I photographed the top one already disconnected; be sure to squeeze the edge tabs to release the clamp hooks. The HDD SATA connector has a convenient pull tab.

ORANGE: On my iMac 24" (early 2008), the main power cord is marked «MLB» and is located in the wifi cables area. My iMac motherboard is a bit different than Jeff's one. But the differences are small. For instance, in my case, there is a small plastic fin above the memory slots that you'll have to bend a little to take out the power and left speaker cables. There is also a small cooler plate in the area above the memory slots.

Alexandre Lourdel - Reply

Wires done. Now to get unscrewed. There are ten T-10 torx screws holding the logic board to the case in three different sizes: Long ones (2.5mm x 24mm)
  • Wires done. Now to get unscrewed. There are ten T-10 torx screws holding the logic board to the case in three different sizes:

    • Long ones (2.5mm x 24mm)

    • Short ones (2.5mm x 7mm)

    • A short one with a fine thread (2.5mm x 7mm)

RED: On my iMac 24" (early 2008), the motherboard has just one more long screw located in the middle of the motherboard, below the top one indicated by Jeff in his picture. All the other screws are like those indicated by Jeff.

Alexandre Lourdel - Reply

If you haven't done so already, remove the speaker assembly on the right by loosening a single T-10 (2.5mm x 14mm) screw. Remove the two T-9 (2mm x 7mm) screws from the bottom right and left corners of the RAM slots that secure the black plastic bracket to the frame.
  • If you haven't done so already, remove the speaker assembly on the right by loosening a single T-10 (2.5mm x 14mm) screw.

  • Remove the two T-9 (2mm x 7mm) screws from the bottom right and left corners of the RAM slots that secure the black plastic bracket to the frame.

  • Now simply lift out the logic board while keeping a careful eye on all those wires you just disconnected. The heatsink fins are attached to the logic board and lift out with it.

  • Note: There is a bit of foil tape on the far right (by the audio ports) that will need to be pulled up from the case as well while you lift out the motherboard.

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The logic board is moved to my padded work surface. Flipping the board over you'll find all the back-panel connectors and some nifty copper heat piping for the CPU and GPU. Those heat pipes flow to fins above the main blower. This is what 4 years of dust accumulation looks like. Is this the reason my VRAM died?
  • The logic board is moved to my padded work surface.

  • Flipping the board over you'll find all the back-panel connectors and some nifty copper heat piping for the CPU and GPU.

  • Those heat pipes flow to fins above the main blower. This is what 4 years of dust accumulation looks like. Is this the reason my VRAM died?

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The graphics card is retained by two T-9 (2mm x 5mm) torx screws on the GPU board... a third T-9 (2mm x 4mm) screw on the end of the heat sink... and the ever-present thermal sensor connector.
  • The graphics card is retained by two T-9 (2mm x 5mm) torx screws on the GPU board...

  • a third T-9 (2mm x 4mm) screw on the end of the heat sink...

  • and the ever-present thermal sensor connector.

  • Remove/disconnect them all.

On my iMac 24" (early 2008) equipped with a Nvidia 8800GS, there are 3 screws too, located at the exact same places than Jeff 's indications. Great job, Jeff ! Thanks again for your help !

Alexandre Lourdel - Reply

You've done it!  The graphics card simply tilts up 45 degrees and slides up out of the MXM connector, heat sink and all. I'm glad I could see just how well engineered this piece of Apple hardware is. In the second photo you can see the replacement graphics card (Apple part #661-5135) I got from Impact Computers in Florida. It's a drop-in replacement. Even the adhesive foam and thermal sensor are already in place. In fact, you better not turn your back or you may forget which is which! You World of Warcraft players out there might agree my son and I thought the old video card makes a pretty authentic-looking Gnomish 1H axe. Glory to the Alliance!  :-)
  • You've done it! The graphics card simply tilts up 45 degrees and slides up out of the MXM connector, heat sink and all. I'm glad I could see just how well engineered this piece of Apple hardware is.

  • In the second photo you can see the replacement graphics card (Apple part #661-5135) I got from Impact Computers in Florida. It's a drop-in replacement. Even the adhesive foam and thermal sensor are already in place. In fact, you better not turn your back or you may forget which is which!

  • You World of Warcraft players out there might agree my son and I thought the old video card makes a pretty authentic-looking Gnomish 1H axe. Glory to the Alliance! :-)

On my iMac 24" (early 2008, Nvidia 8800GS), I had to unscrew 4 screws to release the graphic card from the cooler plate (don't be afraid, it's easy). Then I had to clean all the thermal paste from the upside of the graphic processor using small amount of 90º alcohol (holding the graphic card upside down so that alcohol doesn't pour inside the chips), unglue all the small stickers, then bake the graphic card during 7 min at 200ºC (graphic chip, up), then, after cooling down and reaching ambient temperature, apply small amount of thermal paste (a 2 mm nut) on the graphic chip, then reassemble everything. Voilà ! It's alive ! Infinite thanks to Jeff for his invaluable help !

Alexandre Lourdel - Reply

Conclusion

To reassemble your device, follow these instructions in reverse order. This is a good time to vacuum out all that accumulated dust too!

43 other people completed this guide.

Jeff Dickson

Member since: 02/24/2013

1,313 Reputation

1 Guide authored

22 Comments

Any tips for selecting a replacement gfx card? How can I be sure my purchase will work?

aaaidan - Reply

Aha! The "Apple part number" from step 11 is a great clue! Searching for these cards by this part number yields many online sellers.

There were three cards that could go in this model:

* NVIDIA GT120 (256Mb): part #661-4991

* NVIDIA GT130 (512Mb): part #661-4990

* ATI Radeon HD 4850 (512Mb): part #661-5135

The ATI card is generally marginally cheaper than the equivalent NVIDIA.

aaaidan - Reply

When I bought my iMac new, I remember the ATI card being the top-of-the-line option.

Jeff Dickson - Reply

Hey Jeff

Do you think I can replace the GPU with a unit from a 2011 iMac?

Rob - Reply

If you're going to try and substitute parts, I would start with the website I bought my video card from (http://www.impactcomputers.com/apple-ima...) and see if the video card(s) for that particular 2011 iMac match any of the part numbers aaaidan shows above.

I picked out one of the 2011 iMacs at random on the website and while the actual card looks the same (size and MXM connector) the heat sink is completely different. But you could try and dismantle the heat sink from the old and new cards and swap them. I would love to know if that works. An AMD Radeon HD6750M upgrade would be sweet :)

Jeff Dickson - Reply

Hmm ok, I exchanged the cards today, but as I already feared = screen stays black...

Guess i'll have to buy a GT130

Rob - Reply

Strangely the mac is working, but screen stays black. I can hear Windows boot... maybe theres a trick with EFI flash i.e.

Rob -

Hi. I did it, but separatet the cooler from the grafic-card. Removed als that "cooling-gum" on the RAM's and cleaned the CPU with tissue-paper. Heated my kitchen oven to 200°C, waited untill temp ist reached. Then put my grafic-card inside for exact 5 Minutes. After this, open the oven, DONT TOUCH THE CARD. Switch oven to off. Wait until the card has slowly reached room-temperature. Reassemble (using the cooling-goo on the rams, and some "Wärmeleitpaste (German-word; i am lazy)" on the CPU. Press the coolerplate firmly to the card (all the goo has to be flatened, to gain contact between the cooling plate and the cpu) - Reassembled, WORKS!

For a broken-card... at least worth a try. Dont blame me if it dosent work. There are thousand of threads out there about this topic - inform yourself.

BTW: Card is a NVIDIA GeForce 8800 GS 512 MB

Heiko - Reply

Hello Heiko seems that this would only work on a 8800 (German: glaube nicht dass dies bei einer GT 130m funktioniert). But I shall give it a try

Rob -

Hi, for me the new graphic-card was to expensive. i take the card and put it in my oven for 20 min by 220 degrees. and... it works now. How long? i don't know...

Stefan - Reply

IT WORKED! I baked my card at 200°C (about 400F) for 20 minutes yesterday. Mac is runnung smoothly so far...

Rob -

I had the exact problem as described in the article. Bought a graphics board online. I could not locate any new ones, however, for a mid 2008 iMac. Followed this procedure and the referenced one for opening the iMac. Both very excellent guides. Thank you so much for posting them. I would only reiterate the part about being very careful when pulling up the outer glass. The alignment pins break off very easily. I broke 2 or 3. The good thing is that they don't seem to be essential to the screen as it is held in place very well with the magnets. Thanks again for the excellent guides!

johnnya - Reply

Awesome

Brian - Reply

Hey guys, i replace the card with a Dell G92-751-B1 M17X/M15X Nvidia GTX 260M 1GB MXM 3.0 and it works fine but gamma is too high (it is like take a look to the sun without sunglasses). I tried to low it with same programs but I cannot lower to to an acceptable level (fn f1 and fn f2 keys dont work). I install windows 7 on bootcamp and cannot install any nvidia drivers, always computer tell me that cannot install the specific driver. In mac the System Information card model correctly listed (gtx 260m). Any idea?

havell - Reply

Hi. I have a imac 24 a1225 model. Nvidia Geforce 7600 GT is compatible ?, and geforce GT210 is compatible ?. I expect an answer. Thank you

Adroid Prueba - Reply

Hi, in step 6 on the 3rd picture there is black rounded rectangle little black dot on center. Right of the little orange square. What is it? is this infrared or something else? I broke this part today. is this important or can I live with it?

Murat Ozgul - Reply

Yes, this is the Apple Infrared receiver for the Apple Remote. If you don't have or never used the Apple Remote, you won't be missing anything. I personally use the Apple Remote with Kodi (media player) to stream media, so I would miss it dearly. If you don't have an Apple Remote, you should be able to pick one up for less than $20. Fixing the infrared receiver might be more expensive though...

Miles Raymond -

Great instructions! I replaced my card today with a used one found on Amazon. I took pictures along the way but still maybe something is not hooked up proper. The fan(s) are running at high speed and are audible. Ideas anyone?

ncgater - Reply

Maybe you forgot to plug back some temperature sensor plug. Or maybe you damaged one of its little cables.

Alexandre Lourdel -

I have a iMac 24inch Early 2009 EMC 2267 Model A1225. It was working and now does not display anything and no sound when the power comes on. Could replacing the video card fix the issue? Any suggestions would help. Thank you.

lgalvan - Reply

Great instructions ! I completed your step by step with some instructions about the same process regarding an early 2008 24" iMac with a Nvidia 8800GS (iMac8,1 - A1225 - 2211). I baked the videocard and everything is working fine now ! I'd like to add that, as I took my time to avoid damaging anything, this operation took me more than 5 hours.

Alexandre Lourdel - Reply

Hello,

Did replace My motherboard (Great instructions by the way), got the same symptoms as before.

LED 1 and 2 ON, LED 3 just blink on startup, no Sound. I have tried different RAM modules, same thing.

Any idea ? I have an AMD video card, could it be dead ?

Thanks,

Olivier - Reply

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