AMD Radeon R9 M390X vs AMD Radeon R9 M395X vs AMD Radeon R9 M375

AMD Radeon R9 M390X

The AMD Radeon R9 M390X is a mobile high-end graphics card for laptops. It is most likely based on the same chip as the AMD Radeon R9 M295X in the iMac 5K Late 2014. That means it should be based on the third generation of GCN (desktop Tonga chip). The amount of shader cores is identical but the core clock is reduced by 15% (from 850 MHz to 723 MHz) and the memory is also clocked slower (5448 MHz vs 5000 MHz).

The performance should be a bit below the M295X. Compared to the competition, the R9-M390X should be positioned somewhere between the GeForce GTX 965M and 970M and therefore suitable for high-end games in 1080p resolution and high detail settings.

The card was first mentioned by Alienware on their twitter account and should feature 4GB VRAM according to the tweet.

The power consumption should be rated around 100 Watt TDP and therefore suited only for large and bulky laptops (like the Alienware M17x it was announced in).

AMD Radeon R9 M395X

The AMD Radeon R9 M395X is a mobile high-end graphics card based on the Tonga chip (3rd generation of GCN). It uses all of the 2048 shader cores (32 compute units) as the previous generation R9 M295X but features a slightly higher core clock (+60 MHz). Therefore, the performance should be on a level with the R9 M295X (see for benchmarks).

AMD Radeon R9 M375

The AMD Radeon R9 M375 is a dedicated higher mid-range graphics card for laptops. It is still unclear if the M375 is based on a new chip (Tonga derivative with full DirectX 12 and Vulkan support) or the old Cape Verde chip from 2012. The core is clocked at relatively high 1015 MHz, however, the bottleneck may be the use of slow DDR3 graphics memory (128-bit).

Performance

If slow DDR3 graphics memory is used, the performance should be somewhere close to a Radeon R9 M270 (see for gaming benchmarks). Therefore, demanding games are running in low to medium details.

The 640 shaders can be used with OpenCL 1.2 for general-purpose calculations (as 10 compute units).

Features

Features of the R9-M375 include video decoding for MPEG-4 AVC/H.264, VC-1, MPEG-2, and Flash directly by the AMD GPU. Multi-View Codec (MVC) and MPEG-4 part 2 (DivX, xVid) HD videos are compatible as well.

The R9 series also supports automatic graphics switching between the integrated GPU and discrete GPU. Called Enduro, the technology supersedes AMD's Dynamic Switchable Graphics and is similar to Nvidia's Optimus. Furthermore, the M375 can directly support multiple monitors using Eyefinity Technology if Enduro is disabled.

Other features include ZeroCore to reduce the power consumption when the display is turned off and Power Gating to power down areas of the chip that are not used. 

The integrated HD audio processor is able to transmit HD Audio (TrueHD or DTS Master Audio) over HDMI and DisplayPort (e.g., for Blu-Ray videos). Additionally, it allows audio output simultaneously and in parallel to multiple devices with the new Discrete Digital Multipoint Audio (DDMA) feature.