Radeon HD 4890 1GB vs Radeon R7 250

Intro

The Radeon HD 4890 1GB makes use of a 55 nm design. AMD has set the core frequency at 1000 MHz. The GDDR5 RAM is set to run at a frequency of 975 MHz on this particular card. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 Rasterization Operator Units.

Compare those specifications to the Radeon R7 250, which uses a 28 nm design. AMD has clocked the core frequency at 1000 MHz. The GDDR5 memory works at a frequency of 1150 MHz on this card. It features 384 SPUs as well as 24 TAUs and 8 Rasterization Operator Units.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the max amount of data (measured in megabytes per second) that can be transferred across the external memory interface in a second. It's calculated by multiplying the card's bus width by its memory speed. If it uses DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly record to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.