Upgrading My White 2006 iMac Core Duo to a Core 2 Duo and Installing OS X Lion


Not very long ago I added a post explaining why I didn’t think it would be worth upgrading the processor in my Core Duo iMac and also why I wasn’t in a hurry to upgrade to Lion. Well, as often happens, I wasn’t satisfied with those conclusions and eventually decided that the benefits outweighed the effort involved.

This post won’t include step-by-step instructions – just some general information and maybe a few tips. However, I do think it was indeed worth upgrading my iMac to be able to run Lion.

I managed to find a used Intel T7200 (Socket M) processor on eBay for $45. Installation was a chore, but not impossible. In fact, after you’ve done it one time you won’t have any trouble doing it again. My iMac motherboard didn’t match the one in the Mac|Life upgrade guide, but the process was still nearly identical.

Unfortunately, I seem to have damaged the Airport. I’m not certain which part is bad (the card or the antenna), but I suspect it’s because I did not fully remove the LCD and that the antenna may have been cut or crimped. To deal with this I bought an inexpensive USB wireless N adapter.

For a new processor you’ll need to add thermal paste. However, I didn’t. My processor was used so there was still thermal paste on the replacement processor as well as some left on the heatsink. Sure, it looks old and dried but I think it becomes more fluid once the processor heats up. So far, my CPU temps are in the normal ranges (observed being between 110 F – 150 F).

I had to wait several days before attempting to upgrade the iMac from Snow Leopard to Lion. Fortunately, I already had options. My wife’s laptop had been upgraded from Snow Leopard to Lion, so using her laptop’s Lion recovery data was an option for me. I tried to work with a USB recovery image, but in the end it seems that the only good way to upgrade an unsupported Core 2 Duo Mac is to install Lion using a supported Mac and Target Disk Mode.

So… I set my iMac to boot into Target Disk Mode (System Preferences – Startup Disk, though holding “T” on boot should do the same) and then I started my wife’s Lion laptop from it’s recovery partition. After that, it was just a matter of having the Lion installer use my iMac’s drive for the installation.

The process took several hours. Much of the time was taken by the installer. It seems that before installing it checks to see if the latest Lion installer is available. If not, it downloads the new version. This actually saved me a few steps. Instead of having to install the Lion 10.7.1 and 10.7.2 updates later (and having to delete the plist again after 10.7.2) it installed 10.7.2 to begin with.

After Lion was installed I connected to the iMac hard drive via Target Disk Mode from my wife’s laptop and deleted the System/Library/CoreServices/PlatformSupport.plist file (from my iMac drive). Then I restarted the system and it seems to be working fine aside from a few, rare graphic glitches I had noticed earlier, which seem to be related to certain animations.

Overall, I think it was worth the effort. The system seems to be running fine.

Upgrade Your iMac to a Core 2 Duo Processor (Mac|Life)

Lion on 2006 Mini with Core2Duo CPU upgrade? (MacRumors)

Updated 10/22/2011: Today I attempted to rip a Blu-Ray movie and found the process to be much shorter than it was with the Core Duo processor. The rip from disc only took about an hour and a half (previously about 10 hours). The conversion process looks like it will require about 5-6 hours (instead of 10-12 hours).

Updated 10/26/2011: So far so good. The only other quirk I noticed was that I couldn’t open my iTunes library right away. It seems that in Snow Leopard I had iTunes 10.5 installed but when Lion installed it replaced it with a slightly older version of iTunes (the libraries weren’t compatible). The solution was simple – I only had to download iTunes 10.5 and install it. After that everything worked fine.

Prior to installing Lion I purchased and installed Quicken Essentials for Mac so I could import my data from Quicken 2006 (PowerPC only, so it won’t work in Lion). Like many others, I prefer Quicken 2006, but I didn’t need all of the features and I didn’t care to go with a different software company (at least not yet). I purchased Quicken Essentials at a discount (about half-price) and imported my data. I do have investments and loans but at the end of the day I only use Quicken to balance my checking account and budget for the next month. It seems to handle these basic tasks just fine. Note that you must install Quicken Essentials and import from the older version of Quicken BEFORE upgrading to Lion (otherwise you’ll have to boot from a Snow Leopard disk).

Updated 11/12/2011: I had a link to the discount for Quicken Essentials but it’s no longer available.

16 thoughts on “Upgrading My White 2006 iMac Core Duo to a Core 2 Duo and Installing OS X Lion

  1. Something I’ve been trying to find information on for a long while… The Core Duo iMac’s are limited to just a little over 3GB of ram, but the system will report 4GB as being installed. My only guess to this is either a firmware limitation, or what’s more common is that 32bit machines can only address about 3.3gb of ram. Now that you are running lion, and a Core 2 Duo, you’ll be running in 64bit(I assume), if that’s the case, will your mac now recognize 4GB?

    • Josh – A while back I did some research on installing 4 GBs, well before my intention to upgrade to Lion, and most responses I found in various forums stated that the 3 GBs limit is determined by the motherboard itself and some other posts specifically stated that upgrading the CPU won’t affect that limitation. Here’s one post that includes this type of discussion. I seems that it’s not possible to use the full 4 GB in this iMac though some users think it may make a slight difference performance-wise. I doubt that it would really make much of a difference if you already have 3 GBs installed.

      From what I’ve read I think the OS would be aware of the fact that 4 GBs is installed, but it doesn’t have a way to access it. If I get a chance I’ll see if I have an extra 2 GB RAM module sitting around that’s compatible and install it. At the least, I don’t think it will hurt anything.

  2. Colin Haines

    Did you have to wipe the hard drive of your iMac? Or could you somehow upgrade the iMac without loosing all you data?

    • I was able to upgrade from Snow Leopard to Lion without having to wipe the drive. This technique did require that I install from a Lion recovery partition that was originally purchased via the App Store. As far as I know it won’t work if you try to install Lion from a recovery partition on a system that originally came with Lion (I used the copy that I had purchased for my wife’s MacBook Pro, which was previously Snow Leopard but directly compatible with Lion).

      If you haven’t already checked then you may want to see if the latest release of Lion can be made to work with a Core Duo Mac by deleting the PlatformSupport.plist. I think when I upgraded the iMac to Lion that the installer automatically connected to the Internet, downloaded, and installed the latest version (which is also why the install took several hours).

      • Colin Haines

        I have a MacBook pro that also came with snow leopard. Where do I find the recovery partition?

      • I think it’s automatically added when you upgrade to Lion but hidden by default so it doesn’t show up when you view the drive in Disk Utility. If you want to verify that it exists then you should be able to restart the Lion system and hold Command + R to enter the recovery program.

        If you’re wanting to install Lion on a Mac that was upgraded from a CoreDuo processor to a Core2Duo then you will probably have to start the Mac (that was originally CoreDuo) in Target Disk mode and do the actual install from the newer Lion system. I think it will fail if you don’t because the installer will detect that it’s not operating under a compatible system.

      • I must have used FireWire. It’s been a while since I did the upgrade. Based on other posts I’ve read you can’t use Ethernet for Target Disk Mode.

  3. Colin Haines

    Thanks for your help in this. I have succesfully upgraded my CPU and installed Lion on my early 2006 17″ intel iMac. I also found a website that you can upgrade the firmware so you can put in 3 gb of RAM. Now the trick will be when Mountain Lion comes out, will it run in that…….

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