As you already know, AMD has officially unveiled three SKUs that will be a part of the new Radeon Pro 400 series, including the Radeon Pro 450, Radeon Pro 455 and the Radeon Pro 460. According to the specifications provided on AMD's Radeon.com site, all three of these should be based on Polaris 11 GPU and are pretty much a power-efficient version of the Radeon RX 460 desktop graphics card.
For the purpose of reference, Radeon RX 460 was the only graphics card based on Polaris 11 GPU and feature 896 Stream Processors and offer peak compute performance of 2.2 TFLOPs, but also had a 75W TDP.
In order to fit in Apple's "under 35W power envelope", AMD had to make certain cuts and although we still do not have precise details, it appears that the Radeon Pro 400 series will feature much lower GPU clocks.
The flagship Radeon Pro 460 graphics card features 16 Compute Units (CUs), which adds up to 1024 Stream Processors and offer peak compute performance of 1.86 TFLOPs, which is lower than the RX 460, despite the fact that it has a higher number of Stream Processors. It comes with 4GB of GDDR5 memory and offers 80GBps of memory bandwidth.
The Radeon Pro 455 features 12 CUs, or 768 Stream Processors, offers 1.3 TFLOPs of peak compute performance and has the same memory bandwidth, although it will be equipped with 2GB of GDDR5 memory.
The entry-level SKU is the Radeon Pro 450, which is further cut-down to 10 CUs, or 640 Stream Processors for 1.0 TFLOPs of compute performance. It also comes with 2GB of GDDR5 memory and same 80Gbps memory bandwidth.
Performance-wise, the Radeon Pro 460 should be relatively close to the Radeon RX 460 which is not half bad considering it is squeezed inside a 15.5mm thick notebook chassis and quite a feat considering that AMD had to make a chip that provides at least some GPU performance in a rather tight <35W power envelope.
Hopefully, we will see some performance numbers as soon as first 15-inch MacBook Pro 2016 models start shipping in a few weeks.