
Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly record to its local memory in a second - measured in millions of pixels per second. It is measured in millions of texels processed in a second. The higher this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). This is worked out by multiplying the total texture units of the card by the core clock speed of the chip. Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed per second. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions. The higher the memory bandwidth, the faster the card will be in general. If it uses DDR memory, it should be multiplied by 2 once again.

It's calculated by multiplying the bus width by its memory speed. Memory Bandwidth: Bandwidth is the largest amount of data (in units of megabytes per second) that can be transferred past the external memory interface in one second.
