Introduction

The iMac G3 had onboard video which usually means no upgrade-ability. The iMac developers found a way to allow video upgrade-ability (sort of); they built 2MB on to the logic board to power the ATI 3D Rage Pro Turbo PCI, and added a video ram DIMM slot on the motherboard allowing users to upgrade their video ram using proprietary Apple DIMMs.

  1. The iMac G3. This was a great computer for the time, and had plenty of features.
    • The iMac G3. This was a great computer for the time, and had plenty of features.

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  2. Start by flipping the iMac upside-down. It may help to lay it on a towel, so you don't damage the screen, or scratch the face.
    • Start by flipping the iMac upside-down. It may help to lay it on a towel, so you don't damage the screen, or scratch the face.

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    • Remove this Phillips screw.

    • Using a flathead screwdriver, work your way around the bottom cover, until it comes off.

    • Then, lift the bottom cover up and out, and set it aside.

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    • Now, remove the DB-15 Video connector from the logic board.

    • It may be helpful to use a Phillips screwdriver to remove the thumbscrews.

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    • Remove the power cable from the logic board assembly.

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    • Remove the front panel connector.

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    • Now, remove these Phillips screws.

    • Now, grab the logic board assembly by the piece of plastic, and lift it out.

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    • The logic board assembly. This is the heart of the computer, it contains the motherboard, CPU, RAM, V-RAM, PRAM battery, the hard drive, and the optical drive.

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    • The Video-RAM DIMM slot is located on top of the logic board. Most people confuse this with the system RAM which is hidden under the CPU Shield.

    • The GPU: an ATI 3D Rage Pro Turbo PCI with 2MB onboard + the video RAM DIMM:

    • The Video RAM DIMM:

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    • To remove the V-RAM, push the retaining tabs out, and the DIMM should pop up, then pull it out.

    • The 2MB of V-RAM soldered to the logic board:

    • According to what I've read, the iMac will support 10MB Total V-RAM, 2MB onboard, 8MB DIMM.

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Conclusion

To reassemble your device, follow these instructions in reverse order.

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Chris Green

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One Comment

where can I buy a 8mb video ram chip

Nicholas - Reply

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