We already know that the new 21-inch iMac comes with a 21.5-inch (1920 x 1080 pixel IPS panel, one of Intel’s quad-core Core-i CPUs, AMD Radeon HD 6750M graphics with 512MB, a 500GB HDD, 4GB of RAM, support for Facetime and Intel’s new Thunderbolt I/O technology. This tidy packet will set you back about $1,199 -- not a terrible deal. However, what you’ve got inside that case, you’re kind of stuck with, thanks to Apple’s apparent aversion to creating products that are easy to upgrade at home. Still, where there's a will, there's a way. So, how easy is this machine apart yourself?
iFixit gave it "a very respectable 7 out of 10 Repairability Score" saying that for the most part, the disassembly was pretty straight forward. However, you will need a couple of tools that the average DIYer might not have hanging around. Specifically, a T10 Torx screwdriver and suction cups. If you do happen to have those lying on the work bench, iFixit says you should be able to change the RAM no problem, and replacing the hard drive and optical drive is described as only ‘moderately difficult.’ Things really get tricky for those trying to upgrade CPU/GPU. If that's your plan, you'll have to remove the logic board.
Specific parts found inside the iMac include an LM215WF3 LG display (the same present in the older model), an Intel L102IA84 EFL Thunderbolt port IC, a 2.5 GHz quad-core Intel Core i5-2800S CPU with 6 MB of Intel Smart Cache, an Intel BD82Z68 Platform Controller Hub, a Broadcom BCM57765B0KMLG Integrated Gigabit Ethernet and Memory Card Reader Controller, a Cirrus 4206BCNZ audio controller, a SMSC USX2061 (believed to be a USB 2.0 Hub Controller Family), and an Intersil ISL6364 CRZ Single-Phase Synchronous-Buck PWM voltage regulator for GPU core power applications.
Check out the full tear-down here.