The 21.5″ iMac ships with a 1 TB 5400 rpm hard drive, and the 27″ model bumps that to a faster 7200 rpm drive. Ars Technica reports that the Iris Pro 5200 GPU offers slightly better performance than the GeForce GT 640M GPU found in last year’s entry-level iMac. By integrating this high-speed memory, processes are not slowed nearly as much as when accessing system memory, although we should note that the GPU does use system memory to drive the entry-level 21.5″ iMac’s display. One advantage the Iris Pro graphics has over Intel HD 5000 graphics is that 128 MB of eDRAM memory is integrated into the CPU, which can be used by both the CPU and the GPU.

The big difference this year is using Haswell CPUs instead of the older Ivy Bridge, which should reduce power consumption and heat buildup.Īpple included improved graphics with all but the entry-level 21.5″ model, which settles for integrated Intel Iris Pro 5200 graphics while the rest of the line has nVidia GeForce 700M-series graphics processors. That puts the new low-end 27″ iMac at the same speed as the faster 2012 iMac it replaces. CPU speeds on the 21.5″ models are the same as in last year’s iMacs, but the 27″ model gets a boost to 3.2 and 3.4 GHz.

Imac 27 late 2013 os upgrade