Updated 10/25/2011: Note that despite my comments in this post I decided to upgrade the processor and install Lion. Visit that post for more information. I decided to leave this post since it records what I was thinking at the time and some may still find this information useful.

I was recently disappointed to learn that my iMac, which is an Intel Core Duo system, will not be compatible with OS X Lion (10.7). Core Solo system will also not be supported. At first, I was annoyed. After all, my iMac is still a good system that can run most software rather well, especially considering that it only supports a maximum of 2 GBs of RAM.

However, while I’m still disappointed, I no longer think this is just a strategy to force Mac users to upgrade sooner than necessary. Based on some light reading of several different posts and articles the compatibility cut-off may be an intelligent move. While Snow Leopard does have 64-bit support it runs many system processes and apps in 32-bit mode. The compatibility cut-off for older Intel Macs is apparently attributed to the lack 64-bit support within the Intel Core Duo and Intel Core Solo processors.

Working hard to maintain old code doesn’t always workout very well in the long run. For example, running 16-bit software often caused stability issues with 32-bit versions of Windows. I assume the same could be said of running 32-bit software under a 64-bit operating system. It’s not also just matter of stability but also the inherent necessity to bring forward a considerable amount of old code to keep the older software running. Eventually, this can also lead to bloat. An opportunity for an additional problem can be created in such an environment – some software developers may continue relying on old, obsolete, and sometimes insecure methods that were common with the previous code and methods.

So, while I don’t like the fact that I can’t install Lion on my older Intel Mac, it’s possible that the next several versions of the OS may be more stable then they would be if all of the old code support was brought forward.

I’ve read several posts that demonstrate how to upgrade the Core Duo processor in an iMac and Mac-mini to a Core 2 Duo processor. I’ve considered doing this – from what I’ve read I could find a compatible processor for less that $100.

But, there appears to be a problem. While I can’t say I’ve absolutely confirmed this, I’ve seen enough posts stating that simply upgrading the processor won’t work to deter me from making the attempt. At least, not with a legal version purchased from the App Store and I have no interest in going the illegal torrent route. Lion seems to check more than just the processor. It may be looking at the system firmware, identification, and possibly a number of other hardware attributes. I wouldn’t be surprised if it actually looked for specific, known Mac hardware profiles.

In the end, I don’t think I’ll bother upgrading the processor in the iMac. For Snow Leopard it runs great and since it (apparently) won’t work for Lion I don’t think I’ll get enough boost to make it worth the cost. In my view I’ll be better off putting that $70 – $100 toward a new system.

That’s not to say I’m finished with the iMac just because it can’t take the newest OS version. It will still have a role in our home. In fact, I just ordered a new hard drive to boost it’s capacity from 250 GB up to 1.5 TB. At the least, it may continue to serve as the home automation and media server.

Perhaps this fall I’ll consider purchasing a new Mac for myself. If so, I may get a lower-end MacBook Pro system.

Updated 07/20/2011:

Here are some additional sources that may be useful:

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

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

Upgrading a Core Duo iMac to a Core 2 Duo iMac (MacRumors)

Mac OS X Lion *does* run on Core Duos/Core Solos (MacRumors)