AMD Radeon HD 7650M vs AMD Radeon HD 7640G + HD 7670M Dual Graphics

AMD Radeon HD 7650M

The AMD Radeon HD 7650M (sometimes also called AMD Mobility Radeon HD 7650) is a DirectX11 middle class graphics card for laptops. It is based on the same chip as the Radeon HD 6650M, but has a lower core clock of 450 - 550 MHz. The memory interface is 128 bit wide, but only supports DDR3. The architecture is based on the Northern Islands generation, manufactured in 40nm.

The 480 stream processors should be still based on the "old" 5D architecture similar to the 5000 series. Therefore, the number of shaders is not comparable to the 1D cores of current Nvidia GPUs. The tessellation performance should be improved (like the desktop 6800 series) with the new cards. The stream processors can be used with DirectX 11, OpenGL 4.1, DirectCompute 11 and OpenCL. With the later two the cores can also be used for general computations like transcoding videos.

The 3D performance is similar to the Radeon HD 6630M, depending on the core clock (mostly 500 MHz). Therefore, current games run (more or less) fluently in 1366x768 and medium details. Playing highly demanding games like Anno 2070, a further reduction of the settings could be necessary.

The new UVD3 video decoder supports the decoding of MPEG-4 AVC/H.264, VC-1, MPEG-2, Flash and now also Multi-View Codec (MVC) and MPEG-4 part 2 (DivX, xVid) HD videos on the graphics card.

Furthermore, the HD 7600M series integrates a HD audio controller to transmit HD audio (TrueHD or DTS Master Audio) over HDMI and DisplayPort (e.g. for Blu-Ray videos).

The AMD HD3D Technology offers support for Blu-Ray 3D and 3D displays (integrated and external). However, the solution is not as mature as Nvidias 3D Vision.

Thanks to Eyefinity the graphics chip is able to theoretically drive up to 5 monitors simultaneously. However, this only works if the laptop features enough DisplayPort outputs.

The power consumption of the chip is similar to the Radeon HD 6630M and therefore suited for 15" laptops and up.

AMD Radeon HD 7640G + HD 7670M Dual Graphics

The AMD Radeon HD 7640G + HD 7670M Dual Graphics is the combination of a integrated AMD Radeon HD 7640G APU processor graphics card and a dedicated entry level AMD Radeon HD 7670M graphics card in CrossFire combination. It is called AMD Dual Graphics or asymmetric CrossFire and uses AFR (Alternate Frame Rendering) to render different frames on the two graphic cores. Therefore the combination also suffers from micro stuttering (different spaces between two images lead to stuttering altough the framerate is high enough for fluent gaming with only one GPU).

The performance of the Dual Graphics solution depends greatly on the driver support for the used games. In some games the performance may even degrade by 10-15% compared to using only the APU graphics card. Therefore, due to the micro stuttering and performance problems, Dual Graphics may impose more problems than bring performance gains. Only in a best case scenario the performance is similar to the GeForce GT 635M.

The features like PureVideo HD (UVD3) or OpenCL support are similar to the two graphics cards.

As both graphics cards are rendering frames, the power consumption is clearly higher than using only one GPU.