AMD Radeon R9 M290X Crossfire vs AMD Radeon R9 M275

AMD Radeon R9 M290X Crossfire

The AMD Radeon R9 M290X Crossfire (also known as CF or CrossFireX) is a combination of two high-end graphics cards for big and heavy laptops. Usually, each single R9 M290X renders a single frame in an alternating manner. Therefore, it may suffer from micro stuttering in low frame rates below 30 FPS due to staggering timespans between two frames (e.g., irregular delays between sequential frames). Compared to the Radeon HD 8970M CF, the R9 M290X CF offers exactly the same amount of shaders and the same clock rates.

The R9 M290X is based on the desktop HD 7870 Pitcairn chip with 1280 1D shaders and 80 texture units. The GCN (graphics core next) architecture supports DirectX 12 (FL 11_1) and OpenGL 4.3. More information on the features of the single R9 M290X can be found on the GPU page.

Performance

The Performance of two R9 M290X GPUs in Crossfire mode is just slightly below the Nvidia GeForce GTX 780M SLI, but cannot compete with the GTX 880M SLI. Regardless, modern and demanding games like Battlefield 4 or Metro Last Light are still playable in high resolutions and max. settings with anti-aliasing.

Features

Features of the M290X include the new UVD3 video decoder for decoding MPEG-4 AVC/H.264, VC-1, MPEG-2, Flash, Multi-View Codec (MVC) and MPEG-4 part 2 (DivX, xVid) HD videos directly from the AMD GPU.

The M290 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, each M290X can directly support up to 6 connected monitors using Eyefinity Technology if Enduro is disabled.

Other features of the M290 series include ZeroCore for reducing power consumption when the display is turned off. Power Gating, however, is not supported according to AMD. PowerTune allows automatic overclocking and underclocking of the graphics card as long as the GPU is within its TDP range. 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 now allows audio to output simultaneously and in parallel to multiple devices with the new Discrete Digital Multipoint Audio (DDMA) feature.

Power Consumption

The power consumption of the CF combination is very high (2x 100 Watt) and thus only suited for very large desktop replacement laptops.

AMD Radeon R9 M275

The AMD Radeon R9 M275 is a 28 nm DirectX 12 graphics card based on the GCN (Graphics Core Next) architecture. Built primarily for large laptops, the card is positioned in the upper mid-range category as of 2014. Compared to the old Radeon HD 8870M, the R9 M275 offers a higher core clock speed of up to 925 MHz, while the memory clock stays at 1125 MHz (GDDR5, 4500 MHz). However, some notebook manufactures will choose sligthly slower memory (often 1000 MHz / 4000 MHz effective).

The design of the Radeon R9 M275 has its roots to the Cape Verde chip as found, for example, on the desktop Radeon HD 7770 with 640 1D shader cores and 40 texture units. The core clock of the 8870M, however, is only 925 MHz versus the 1000 MHz of the HD 7770.  

As a result, general performance of the R9 M275 is somewhat below the HD 7770 desktop card or the Nvidia GeForce GTX 760M. Most games of 2014 can be played fluently in high detail settings and resolutions, some older titels even with additional AA/AF. In some very demanding titels like Battlefield 4, medium settings and a resolution of 1366 x 768 pixels may be necessary for sufficient frame rates.

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

Features of the R9 series include video decoding via UVD3 for decoding MPEG-4 AVC/H.264, VC-1, MPEG-2, and Flash directly from the AMD GPU. Multi-View Codec (MVC) and MPEG-4 part 2 (DivX, xVid) HD videos are now compatible as well.

The Radeon R9 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 M275 can directly support up to 6 connected 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.

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 now allows audio to output simultaneously and in parallel to multiple devices with the new Discrete Digital Multipoint Audio (DDMA) feature.

Power consumption of the R9 M275 should be around 60 W. Therefore, the GPU is only suited for larger laptops and DTRs.