Radeon HD 4770 vs Radeon HD 4850 2GB

Intro

The Radeon HD 4770 makes use of a 40 nm design. AMD has clocked the core frequency at 750 MHz. The GDDR5 RAM works at a frequency of 800 MHz on this particular model. It features 640(128x5) SPUs as well as 32 Texture Address Units and 16 Rasterization Operator Units.

Compare all that to the Radeon HD 4850 2GB, which uses a 55 nm design. AMD has clocked the core speed at 625 MHz. The GDDR4 RAM is set to run at a speed of 993 MHz on this particular model. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 Rasterization Operator Units.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the maximum amount of data (in units of megabytes per second) that can be transferred past the external memory interface in a second. It is calculated by multiplying the card's interface width by its memory speed. In the case of DDR type RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics card could possibly record to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.