GeForce 8800 Ultra vs GeForce GT 640 DDR3

Intro

Compare that to the GeForce GT 640 DDR3, which comes with 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 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce 8800 Ultra		171 Watts
	Difference: 106 Watts (163%)

Memory Bandwidth

Performance-wise, the GeForce 8800 Ultra should theoretically be a lot better than the GeForce GT 640 DDR3 in general. (explain)

GeForce 8800 Ultra		103680 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 46656 (82%)

Texel Rate

The GeForce 8800 Ultra should be much (approximately 36%) better at texture filtering than the GeForce GT 640 DDR3. (explain)

GeForce 8800 Ultra		39168 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 10368 (36%)

Pixel Rate

If running with a high resolution is important to you, then the GeForce 8800 Ultra is a better choice, but only just. (explain)

GeForce 8800 Ultra		14688 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 288 (2%)

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 largest amount of data (counted in MB per second) that can be transferred past the external memory interface in one second. It's worked out by multiplying the bus width by its memory speed. In the case of DDR type memory, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the faster 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 in one second. This is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly write to the local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as 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 - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.