GeForce 9800 GT 1GB vs GeForce GT 640 DDR3

Intro

The GeForce 9800 GT 1GB uses a 65/55 nm design. nVidia has set the core frequency at 600 MHz. The GDDR3 RAM runs at a frequency of 900 MHz on this card. It features 112 SPUs as well as 56 TAUs and 16 ROPs.

Compare those specifications to the GeForce GT 640 DDR3, which has clock speeds of 900 MHz on the GPU, and 1782 MHz on the 2048 MB of DDR3 memory. It features 384 SPUs as well as 32 TAUs and 16 ROPs.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the largest amount of data (measured in megabytes per second) that can be moved past the external memory interface in a second. It's worked out by multiplying the bus width by the speed of its memory. If it uses DDR memory, it must 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 AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card could possibly write to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.