The iMac "Core i5" 2.7 21.5-Inch Aluminum features a 22 nm Quad Core 2.7 GHz Intel "Core i5" I5-3335S (Ivy Bridge) processor with four independent processor cores on a single chip, a 6 MB shared level 3 cache, 8 GB of 1600 MHz DDR3 SDRAM (which is not intended to be upgraded after purchase), a 1 TB (5400 RPM) hard drive, and a NVIDIA GeForce GT 640M graphics processor with 512 MB of dedicated GDDR5 memory. It also has a built-in "FaceTime HD" webcam and stereo speakers, but lacks an optical drive.

This model has a 21.5" 1920x1080 LED-backlit 16:9 widescreen IPS display with the "cover glass fully laminated to the LCD and anti-reflective coating." The rear of the case is aluminum and is thicker in the middle and tapers to a razor thin 5 mm at the edges.

Connectivity includes four USB 3.0 ports, dual Thunderbolt ports, Gigabit Ethernet, 802.11n, and Bluetooth 4.0.

In addition to a thinner case design, the "Late 2012 Onwards" iMac models have faster processors, faster architectures, faster RAM (although it cannot be upgraded easily in the 21.5-Inch models), faster graphics, as well as different connectivity than the "Mid-2011" iMac line replaced.