The iMac "Core i5" 3.3 27-Inch Aluminum (Mid-2015/Retina 5K) features a 22 nm "Haswell" Quad Core3.3 GHz Intel "Core i5" (4590) processor with four independent processor cores on a single chip, a 6 MB shared level 3 cache, 8 GB of 1600 MHz DDR3 SDRAM (PC3-12800) installed in pairs (two 4 GB modules), a 1 TB 7200 RPM hard drive, and a AMD Radeon R9 M290 graphics processor with 2 GB 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 27" 5120x2880 LED-backlit 16:9 widescreen IPS display that Apple has dubbed "Retina 5K". 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 2 ports, Gigabit Ethernet, 802.11ac Wi-Fi (802.11a/b/g/n backwards compatible), and Bluetooth 4.0.