The iMac "Core i5" 2.7 21.5-Inch Aluminum (Mid-2011) is powered by a Quad Core 2.7 GHz Intel "Core i5" I5-2500S (Sandy Bridge) processor with a dedicated 256k level 2 cache for each core and a 6 MB shared level 3 cache. In lieu of a system bus, it has a "Direct Media Interface" (DMI) that "connects between the processor and chipset" at 5 GT/s.