GeForce 9800 GT 1GB vs GeForce GT 640 DDR3

Intro

The GeForce 9800 GT 1GB has a GPU core clock speed of 600 MHz, and the 1024 MB of GDDR3 memory is set to run at 900 MHz through a 256-bit bus. It also features 112 Stream Processors, 56 Texture Address Units, and 16 ROPs.

Compare those specs to the GeForce GT 640 DDR3, which features GPU clock speed of 900 MHz, and 2048 MB of DDR3 memory running at 1782 MHz through a 128-bit bus. It also features 384 Stream Processors, 32 TAUs, and 16 ROPs.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the largest amount of data (measured in MB per second) that can be moved past the external memory interface in one second. It's worked out by multiplying the interface width by its memory clock speed. If it uses DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.