GeForce GT 640 DDR3 vs GeForce GTS 450

Intro

The GeForce GT 640 DDR3 features a core clock speed of 900 MHz and a DDR3 memory frequency of 1782 MHz. It also features a 128-bit bus, and uses a 28 nm design. It is made up of 384 SPUs, 32 TAUs, and 16 Raster Operation Units.

Compare those specifications to the GeForce GTS 450, which features a core clock speed of 783 MHz and a GDDR5 memory frequency of 902 MHz. It also uses a 128-bit bus, and uses a 40 nm design. It is comprised of 192 SPUs, 32 TAUs, and 16 ROPs.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the maximum amount of data (in units of MB per second) that can be transported over the external memory interface in a second. The number is calculated by multiplying the bus width by its memory speed. If it uses DDR type RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

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