I'm up grading my Apple iMac 2.16GHz Intel Core 2 Duo (20-inch) with two, 2GB DDR2 PC2-5300 • CL=5 • Unbuffered • NON-ECC • DDR2-667 • 1.8V • 256Meg x 64. (One stick for each slot). This is the "Late 2006" iMac
Can I use the two, 1 GB Memory sticks I take out of this machine and use them to up grade (one in each slot) myApple iMac 2.0GHz Intel Core Duo (20-inch). This is the "Early 2006" iMac.
The specs on the 1GB memory from the late 2006 appear to the same that is needed for the 1GB memory for the early 2006. The only difference may be the Meg rating.
Yes, these two systems take the same memory up to the 1GB modules. You should be able to safely install the 1GB modules from the 2.16GHz system into the 2.0GHz system. One thing I did notice however. The iMac 2.16 I show as having a max memory of 3GB (2GB + 1GB). If you install 4GB into this system, you could possibly run into issues. Just a heads up for you before it happens.