GeForce 8800 GTX vs GeForce GT 640 DDR3

Intro

Compare those specs to the GeForce GT 640 DDR3, which has a clock frequency of 900 MHz and a DDR3 memory frequency of 1782 MHz. It also uses a 128-bit memory bus, and makes use of a 28 nm design. It is comprised of 384 SPUs, 32 TAUs, and 16 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce 8800 GTX		155 Watts
	Difference: 90 Watts (138%)

Memory Bandwidth

The GeForce 8800 GTX should theoretically perform quite a bit faster than the GeForce GT 640 DDR3 overall. (explain)

GeForce 8800 GTX		86400 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 29376 (52%)

Texel Rate

The GeForce 8800 GTX should be much (more or less 28%) better at AF than the GeForce GT 640 DDR3. (explain)

GeForce 8800 GTX		36800 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 8000 (28%)

Pixel Rate

If running with high levels of AA is important to you, then the GeForce GT 640 DDR3 is superior to the GeForce 8800 GTX, though not by far. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 8800 GTX		13800 Mpixels/sec
	Difference: 600 (4%)

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: Memory bandwidth is the max amount of information (measured in MB per second) that can be moved across the external memory interface in one second. The number is worked out by multiplying the interface width by its memory speed. If the card has DDR RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to its local memory in one 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 - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends 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 maximum fill rate.