For those out of the loop, the RX 480 Polaris is AMD's first FinFET 14nm GPU and part of their fourth generation GCN architecture. The Radeon RX 480 boasts 36 compute units, 2304 stream processors, a 1120MHz base clock speed with 1266Mhz boost clock speed, up to 5.8 TFLOPS of compute power, 256-bit GDDR5 video memory, and has a 150 Watt TDP. With a 150 Watt TDP, just a single 6-pin PCI-E power connector is required. The $199 card ships with 4GB of video memory where as for $239+ is 8GB of the GDDR5 video memory.
In the reviewer material AMD sent over to us in advance, they claim that the Radeon RX 480 delivers 14% greater performance per compute unit over the Radeon R9 290. They also claim the Radeon RX 480 has 1.9x the performance-per-Watt of a Radeon R9 290.