GeForce 8800 GT 256MB vs GeForce GT 640 DDR3

Intro

Compare all that to the GeForce GT 640 DDR3, which has 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 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce 8800 GT 256MB		105 Watts
	Difference: 40 Watts (62%)

Memory Bandwidth

Performance-wise, the GeForce GT 640 DDR3 should theoretically be a lot better than the GeForce 8800 GT 256MB overall. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce 8800 GT 256MB		44800 MB/sec
	Difference: 12224 (27%)

Texel Rate

The GeForce 8800 GT 256MB will be a little bit (about 17%) faster with regards to texture filtering than the GeForce GT 640 DDR3. (explain)

GeForce 8800 GT 256MB		33600 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 4800 (17%)

Pixel Rate

The GeForce GT 640 DDR3 will be quite a bit (approximately 50%) more effective at full screen anti-aliasing than the GeForce 8800 GT 256MB, and also able to handle higher screen resolutions more effectively. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 8800 GT 256MB		9600 Mpixels/sec
	Difference: 4800 (50%)

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 largest amount of information (measured in megabytes per second) that can be transferred over the external memory interface in a second. It is worked out by multiplying the bus width by the speed of its memory. If the card has DDR memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster 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 number of texture map elements (texels) that are applied in one second. This is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly record to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines 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 output rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.