GeForce 8800 GS vs GeForce GT 640 DDR3

Intro

Compare all of that to the GeForce GT 640 DDR3, which features 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 Texture Address Units and 16 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce 8800 GS		105 Watts
	Difference: 40 Watts (62%)

Memory Bandwidth

In theory, the GeForce GT 640 DDR3 will be 49% faster than the GeForce 8800 GS overall, due to its higher bandwidth. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce 8800 GS		38400 MB/sec
	Difference: 18624 (49%)

Texel Rate

The GeForce GT 640 DDR3 will be a little bit (approximately 9%) faster with regards to anisotropic filtering than the GeForce 8800 GS. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce 8800 GS		26400 Mtexels/sec
	Difference: 2400 (9%)

Pixel Rate

The GeForce GT 640 DDR3 will be a lot (more or less 118%) more effective at anti-aliasing than the GeForce 8800 GS, and should be able to handle higher resolutions while still performing well. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 8800 GS		6600 Mpixels/sec
	Difference: 7800 (118%)

Please note that the above 'benchmarks' are all just theoretical - the results were calculated based on the card's specifications, and real-world performance may (and probably will) vary at least a bit.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the max amount of data (measured in MB per second) that can be transported across the external memory interface within a second. It's calculated by multiplying the bus width by its memory speed. If the card has DDR memory, it must be multiplied by 2 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 AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed in one second. This 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 card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one 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 number is calculated by multiplying the number of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.