AMD Radeon R7 M270 vs AMD Radeon R7 M275DX

AMD Radeon R7 M270

The AMD Radeon R7 M270 is a (lower) mid-range DirectX 12 graphics card for laptops. Just like the older Radeon HD 8750M and Radeon R7 M265, it is based on the Mars chip (28nm GCN architecture) with 384 shader cores, 24 TMUs and 8 ROPs. The core is clocked at up to 825 MHz and can access up to 4 GB of DDR3 memory (900 - 1000 MHz, 128 bit).

Performance

The performance of the Radeon R7 M270 is similar to the Nvidia GeForce 830M and GeForce GT 740M. Current and demanding games of 2014/2015 will run fluently only in low resolutions and detail settings. In older games, however, higher quality settings will be possible.

The 384 shaders can be used with OpenCL 1.2 for general-purpose calculations (as 6 compute units). Compared to old TeraScale 2 chips, the GCN-based Mars architecture offers improved performance in this framework.

Features

Features of the R7 M270 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 R7 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 M270 can directly support multiple monitors using Eyefinity Technology if Enduro is disabled.

Other features include ZeroCore for reducing power consumption when the display is turned off and Power Gating to power down areas of the chip that are not used. PowerTune allows automatic overclocking and underclocking of the graphics card as long as the GPU is within its TDP limit. For example, the chip may be underclocked when running FurMark and OCCT, but will overclock in certain games like Lost Planet, Crysis or Resident Evil 5.

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.

Power consumption

The power consumption should be similar to the old Radeon HD 8750M or the Nvidia GeForce GT 730M (30 W or lower). As a result, the R7 M270 is best suited for 13-inch notebooks or larger.

AMD Radeon R7 M275DX

The AMD Radeon R7 M275DX is a Hybrid Crossfire combination of the integrated Kaveri Radeon R7 and a dedicated Radeon R7 M260, M260X, M265, or M265X (called Dual Graphics - DX). Both graphics cards use the AFR mode (alternate frame rendering) to each render a frame. Around 30 fps this Dual Graphics combination may suffer from micro stuttering due to different frame latencies.

The performance depends on the driver support for the used game. In some cases the game engine will only use the dedicated graphics card and therefore the M275DX may not be faster than e.g. a M260 alone. The other end of the spectrum are performance gains of up to 61% in our tests (Alien Isolation Benchmark with high detail settings). This was measured with an ideal combination of a FX-7600P and a M260 with dual channel main memory configuration. On average we measured a 13% increase compared to disabled Dual Graphics when testing 25 games. Looking only at the games that gain from Dual Graphics, the M275DX was able to gain 34% (see diagram below). However, there are some games where Dual Graphics is even slower than with disabled settings, so the user might need to test the settings out. With some games and enabled dual graphics we also experienced problems (e.g., stuttering and flickering main menus in F1 2014 and Shadow of Mordor, wrong texture settings in Ryse, hanging game in Thief, graphical problems with Fifa 15 and Dragon Age: Inquisition).

The shaders of both GPUs can be used for OpenCL calculations and therefore make use of both GPUs.

Furthermore, the M275DX supports Mantle (only light gains in some scenarios in our tests), Eyefinity and Enduro to in battery mode (use of the integrated GPU alone).

The maximum power consumption can be quite high using Dual-Graphics as both GPUs of the APU and the dedicated graphics card are running.