21″ iMac (Mid 2011)

For 2011, the entire iMac line goes quad-core with Core i5 CPUs (and even faster i7 build-to-order options), moves to Intel’s Sandy Bridge chipset, gets Turbo Boost 2.0 technology, adopts the next generation of AMD Radeon HD graphics processors, and gains the Thunderbolt technology introduced with the Early 2011 MacBook Pro models.

Mid 2010 iMacs

The entry-level iMac has 4 GB of RAM, a 500 GB hard drive, and Apple’s aluminum keyboard and Magic Mouse. All other models ship with a 1 TB hard drive and even more powerful Radeon graphics.

The Mid 2011 iMac shipped with OS X 10.6.7 and will support OS X 10.9 Mavericks when it ships.

Apple now offers a solid-state drive (SSD) option on all iMacs except for the 2.5 GHz 21.5″ model, an improvement over the 2010 iMac, where only the top-end model had SSD as a build-to-order option. With the 2.7 GHz and faster models, you can choose to replace the hard drive with a 256 GB SSD or have both a hard drive and an SSD installed, an Apple first. The 2011 iMac EFI Update, released 2011.05.05, enables 6 GBps SATA for even faster drive performance.

With all these changes, the iMac looks like it has ever since Apple moved to 21.5″ and 27″ screens in October 2009.

CPU speeds start at 2.5 GHz, and there’s a 2.8 GHz i7 option for the 2.7 GHz model, which adds $200 to its price.

Apple has improved AirPort performance by building three WiFi antennas into the new iMac, allowing three channels with 150 Mbps bandwidth for a maximum bandwidth of 450 Mbps.

The 21.5″ iMac has the same 1920 x 1080 pixel resolution as high-def television, and the display is LED backlit. The SD Card slot, located on the right side below the SuperDrive, supports SDXC.

Apple’s wireless keyboard is standard, as is the Magic Mouse. The new iMac can be ordered with Apple’s Magic Trackpad.

4 GB of RAM remains standard across the line, and maximum RAM stands at 16 GB using four 4 GB modules.

The base 2.5 GHz model has AMD Radeon HD 6750M graphics with 512 MB of dedicated memory. The 2.7 GHz model uses Radeon 6770M graphics with 512 MB of video memory.

The Mid 2011 iMacs have 4 USB 2.0 ports, FireWire 800 (which is backward compatible with 400), gigabit ethernet, 802.11n WiFi, Bluetooth 2.1+EDR, an SDXC Card slot, and an 8x SuperDrive.

Intel-based Macs use a partitioning scheme known as GPT. Only Macintel models can boot from GPT hard drives. Both PowerPC and Intel Macs can boot from APM (Apple’s old partitioning scheme) hard drives, which is the format you must use to create a universal boot drive in Leopard. PowerPC Macs running any version of the Mac OS prior to 10.4.2 cannot mount GPT volumes. PowerPC Macs won’t let you install OS X to a USB drive or choose it as your startup volume, although there is a work around for that.


  • introduced 2011.05.03 at US$1,199 (2.5 GHz i5, Radeon 6750M) and US$1,499 (2.7 GHz, Radeon 6770M)
  • Part no.: MC309 (2.5 GHz), MC509 (2.7 GHz)

Mac OS

  • Requires Mac OS X 10.6.7 or later. macOS 10.4 Mojave and later are not supported.
  • Mac OS X 10.6 Snow Leopard compatibility
    • Grand Central Dispatch is supported.
    • 64-bit operation is supported.
    • OpenCL is supported.
  • OS X 10.8 Mountain Lion compatibility
    • AirPlay Mirroring is supported.
    • AirDrop is supported.
    • Power Nap is not supported.

Core System

  • CPU: 2.5 or 2.7 GHz quad-core Intel Core i5, 2.8 GHz i7 option ($200 additional)
  • L2 cache: 6 MB shared cache on CPU
  • Bus: 1333 MHz
  • RAM: 4 GB, expandable to 16 GB using four 1333 MHz DDR3 SDRAM
  • Performance:
    • Speedmark 6.5: 215 (2.5 GHz), 223 (2.7 GHz)
    • Geekbench 2: 7185 (2.5 GHz), 7926 (2.7 GHz)


  • GPU, 2.5 GHz: AMD Radeon HD 6750M with 512 MB dedicated VRAM
  • GPU, 2.7 GHz: AMD Radeon HD 6770M with 512 MB dedicated VRAM
  • Display: 21.5″ 1920 x 1080 LED backlit flat panel display
  • Video out: Mini DisplayPort, DVI and VGA with optional adapters


  • drive bus: 3 Gbps SATA Rev. 2 (6 Gbps with EFI update)
  • SSD: 256 GB build-to-order option, can be installed in addition to hard drive
  • Hard drive: 500 GB/1 TB 7200 rpm SATA drive, 2 TB option
  • SuperDrive: writes DVD±R, DVD+R, and DVD+RW discs at up to 8x speed, DVD-RW at up to 6x; dual layer at up to 4x; reads DVDs at up to 8x, writes CD-R discs at up to 24x, writes CD-RW discs at up to 16x, reads CDs at up to 24x


  • Thunderbolt: 1 port
  • USB: 4 USB 2.0 ports
  • FireWire 400: none
  • FireWire 800: 1 port, 7 Watts
  • Ethernet: 10/100/gigabit
  • WiFi: 802.11n AirPort Extreme built in, three antennas support up to 450 Mbps bandwidth
  • Bluetooth 2.1: included
  • IR receiver: supports Apple Remote (not included)
  • SD Card: 1 slot, supports SDXC
  • Microphone: internal
  • Modem: No longer offered by Apple


  • H x W x D: 17.75 x 20.8 x 7.42 in/45.1 x 52.8 x 18.85 cm
  • Weight: 20.5 lb/9.3 kg
  • Power supply: 241W

CPU Upgrades

  • none

Online Resources