The first three generations of Intel-based iMacs use the same Socket M to mount the CPU and have a 667 MHz system bus. The CPU is not soldered in place, allowing the Early 2006, Mid 2006, and Late 2006 iMacs to take the same CPU upgrades, bringing speeds as high as 2.33 GHz.
Original speeds for 2006 iMacs were:
- 1.83 GHz Core Duo (17″ Early 2006 and Mid 2006)
- 2.0 GHz Core Duo (20 ” Early 2006 and Late 2006)
- 1.83 GHz Core 2 Duo (17″ Late 2006, education model)
- 2.0 GHz Core 2 Duo (17″ Late 2006)
- 2.16 GHz Core 2 Duo (17″, 20″, and 24″ Late 2006)
- 2.33 GHz Core 2 Duo (20″ and 24″ Late 2006)
There is no faster CPU for the 2.33 GHz iMacs. That is already the fastest Socket M processor Intel ever made.
It’s possible to upgrade these with up to a 2.33 GHz Core 2 Duo Merom CPU. These are your Core 2 Duo CPU upgrade options:
- 2.0 GHz Intel T7200, 4 MB cache, about $3 on eBay
- 2.16 GHz Intel T7400, 4 MB cache, about $9 on eBay
- 2.33 GHz Intel T7600, 4 MB cache, $26 and up on eBay
Only consider the 2.0 GHz T7200 if you have a Core Duo iMac or the 1.83 GHz Core 2 Duo model. With its larger cache and more efficient CPU, it will give a modest performance boost for about $3 shipped – about 7% better than 2.0 GHz Core Duo and 15% better than 1.83 GHz. Be sure to get good thermal paste, such as Arctic Silver.
The 2.16 GHz T7400 provides maybe 5% more overall power than the T7200, and you can often find it for under $9 shipped on eBay. Definitely worth it for the 1.83 GHz iMacs and the 2.0 GHz Core Duo – maybe not worth the effort on the 2.0 GHz Core 2 iMac.
For the maximum speed on these iMacs, you’re looking at the 2.33 GHz T7600, which provides a 16% speed boost for the 2.0 GHz Core 2 model and over 25% for the 1.83 GHz iMacs. Again, it may not be as worthwhile for the 2.16 GHz model, as this is only about a 6% difference in benchmark scores.
Geekbench 2 Scores
These are rough averages under Geekbench 2. The amount of installed memory makes a difference in Geekbench scores – more RAM will give you a higher score.
- 1.83 GHz Core Duo, 2365
- 2.0 GHz Core Duo, 2575
- 2.o GHz Core 2 Duo, 2775
- 2.16 GHz Core 2 Duo, 2900
- 2.33 GHz Core 2 Duo, 3075
Note that upgrading a Core Duo iMac with a Core 2 Duo CPU does not allow it to use more than 2 GB of RAM or install Mac OS X 10.7 Lion unless you update the EFI firmware to version 5,1. Be sure to install the Core 2 Duo CPU before performing the firmware update, which makes it the equivalent of a native Core 2 Duo iMac, so you can install 4 GB of memory and/or OS X Lion.
Keywords: #early2006imac #mid2006imac #late2006imac #socketm #cpuupgrade #coreduoimac #imaccoreduo
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