Radeon HD 3870 X2 1GB vs Radeon R5 M255

Intro

The Radeon HD 3870 X2 1GB makes use of a 55 nm design. AMD has clocked the core speed at 825 MHz. The GDDR4 memory is set to run at a frequency of 1126 MHz on this model. It features 320(64x5) SPUs along with 16 Texture Address Units and 16 Rasterization Operator Units.

Compare those specifications to the Radeon R5 M255, which comes with a core clock frequency of 940 MHz and a DDR3 memory speed of 1000 MHz. It also makes use of a 64-bit bus, and uses a 28 nm design. It features 320 SPUs, 20 Texture Address Units, and 8 ROPs.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the max amount of information (in units of MB per second) that can be transferred past the external memory interface within a second. It is worked out by multiplying the interface width by its memory clock speed. If the card has DDR type RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied in one second. This figure is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.