Upgrading 20" CD iMac - JUST DO IT!

Discussion in 'iMac' started by MacDann, Dec 20, 2011.

  1. MacDann macrumors 6502a


    Mar 27, 2007
    Can see the end of the Earth from here
    I have an early 2006 20" iMac with a CoreDuo processor and 2GB of RAM. Since this prevented me from upgrading to Lion, I set out to find a newer C2D iMac in the Marketplace.

    While doing so, someone pointed out to me that in fact the processor on my particular model of iMac was socketed, and that it could be upgraded to a Core2Duo processor. So here is what I did:

    1.) Purchased a T7600 (2.3GHz C2D) processor off of eBay. Suffice to say there are tons of people selling working pulls that are guaranteed, and I was able to find one for $105 including shipping. The median price seemed to be around $110/$120 from reputable sellers.

    2.) Using the iFixit guide, I disassembled my iMac and replaced the processor. Not a job for the uninitiated, but not bad if you've been under the hood of a laptop with a bunch of Torx drivers. Just take your time and be careful, that's all.

    3.) Since my iMac was nearly six years old, I took the opportunity to replace the CMOS battery while I was under the hood. An easy thing to do, and readily available at any WalMart or Radio Shack for a few bucks.

    4.) I also replaced the stock 250GB hard drive with a 750GB Seagate Barracuda, which was a mistake on my part due to the heat it generated. It died within a week due to overheating. My fault, as I should have run the SMC fan control utility and bumped the fan speeds up a bit to deal with the added heat load. Please learn from my mistake if you do this.

    5.) After everything was reassembled, I installed a patched copy of Lion so the OS would install. The instructions on how to do this are in this thread.

    Now for the fun part.

    Since EFI limitations prevented the system from exceeding the 2GB RAM limit, I poked around on the Web and found a guy who has written an EFI update for this particular machine/motherboard that removes the limit. You can find the instructions and installer here. Do note that to access the download you have to join the forum.

    6.) I ran the EFI upgrade utility and voila! Now the machine is recognized as the C2D model, AND it recognizes more than 2GB of RAM.

    I only had one 2GB SODIMM, so the question of the 3GB limit was still in place.

    I got another 2GB SODIMM from OWC today, and guess what? I now have 4GB of RAM in the machine, and the OS and hardware recognize it!

    For the grand total of about $165 and some time, I now have a 2.3GHz C2D iMac with 4GB of RAM happily running OS 10.7.2. Granted, the next update could potentially break this, but that is something I can control.

    If anyone has any questions, please ask.


    Attached Files:

  2. Intell macrumors P6


    Jan 24, 2010
    Very nice. I've done a similar upgrade to my early 2006 Mac Mini.
  3. LPZ macrumors 65816

    Jul 11, 2006
    No mean feat

    I replaced a failed HD in the same model iMac. Took care of the battery at the same time. Thought seriously about upgrading the CPU, but decided there was no real advantage in putting in a Core 2 Duo.

    Having used Lion on another machine, I'm glad I didn't bother. What a disappointing OS (to me, so far).

    Anyway, nice job doing that upgrade. Knowing what's involved, it certainly a non-trivial accomplishment.
  4. alksion macrumors 68000


    Sep 10, 2010
    Los Angeles County
    Seems like a little too much work for the benefit, but hey, in this economy, I completely understand why you did so. Not everyone has $1200 lying around for a new iMac and thus, you saved yourself a lot of money.
  5. MacDann thread starter macrumors 6502a


    Mar 27, 2007
    Can see the end of the Earth from here
    "a little too much work?"

    I'm not a cheapskate and could afford a new iMac, but I find it really difficult to justify having to buy a whole new computer just because I want to move up to the latest operating system. Granted, my iMac is six years old, but in all honesty, there is little that it can't do outside of the newer Lion features.

    Apple is sandboxing this stuff a bit much, considering that many of the cross platform features aren't restricted by the age of the OS. Cutting Leopard out for these was a real slap in the face to Mac users, in my opinion, and believe me, I let Tim Cook know about it, too.

    I probably spent a grand total of an hour doing the CPU swap and the $165 for the CPU and 4GB of memory are hardly an expense compared to even buying a later version used iMac. I have to believe that this update will give me at least another 3-4 years of use out of the machine. Add the cost of the update and the computer when I bought it and it amortizes down to about $100/year - not a bad deal, and not something many can match without having to buy new hardware...




    Had I gone to the expense of buying a new or used iMac to accomplish the same I would have been really disappointed....


Share This Page