AMDs two upcoming GPUs based upon Polaris architecture might see a different configuration, at least that's what tpu claims according to industry sources. AMD would be planning a mainstream and performance-segment GPU which kind off confirms already what we discussed, a R9 470 and 480 was expected initially.
However, TPU writes that the performance-segment chip called "Ellesmere," would feature 32 compute units (CUs), and not the previously suggested 40. Per CU there are 64 shader processors, so that would indicate to be a drop from 2560 shader processors, towards 2048 shader processors. And that's a pretty significant difference.
It is also stated that this product would be able to perform at 5.5 TFLOP/sec for single-precision floating point performance, which is very close to Hawaii/Grenada aka the Radeon R9 390 series. Hawaii uses a lot of power though, a 250W TDP. The new chip would use 150W only, which is good news. it is drawing it's power from one single 8-pin power connector.
Memory wise it is suggested to get GDDR5 memory at 7 Gbps (effective). Obviously some features will be upgraded like support for HVEC/H.265 hardware encode/decode acceleration, DisplayPort 1.3, and HDMI 2.0a outputs.
The lower specced mainstream part called "Baffin" would only get 14 CU x 64 = 896 shader processors, which quite honestly seems to be a too low number and sounds more of an equivalent to the 360 series. This part has a peak single-precision floating-point performance rated at 2.5 TFLOP/s. The TDP is rated at just 50W, and it is expected to feature a 128-bit wide GDDR5 memory interface, holding 4 GB of memory.