GeForce 9800 GTX+ vs GeForce GT 640 DDR3

Intro

The GeForce 9800 GTX+ makes use of a 55 nm design. nVidia has clocked the core frequency at 738 MHz. The GDDR3 RAM is set to run at a speed of 1100 MHz on this particular card. It features 128 SPUs along with 64 Texture Address Units and 16 Rasterization Operator Units.

Compare those specifications to the GeForce GT 640 DDR3, which makes use of a 28 nm design. nVidia has set the core speed at 900 MHz. The DDR3 RAM runs at a speed of 1782 MHz on this particular card. It features 384 SPUs along with 32 Texture Address Units and 16 Rasterization Operator Units.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the maximum amount of information (measured in MB per second) that can be transferred over the external memory interface within a second. The number is calculated by multiplying the bus width by the speed of its memory. In the case of DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to the local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.