GeForce 8400 GS 512MB vs GeForce GT 640 DDR3

Intro

Compare that to the GeForce GT 640 DDR3, which features GPU clock speed of 900 MHz, and 2048 MB of DDR3 memory running at 1782 MHz through a 128-bit bus. It also is made up of 384 Stream Processors, 32 TAUs, and 16 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8400 GS 512MB		40 Watts
GeForce GT 640 DDR3		65 Watts
	Difference: 25 Watts (63%)

Memory Bandwidth

The GeForce GT 640 DDR3 should in theory be quite a bit faster than the GeForce 8400 GS 512MB in general. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce 8400 GS 512MB		6400 MB/sec
	Difference: 50624 (791%)

Texel Rate

The GeForce GT 640 DDR3 is a lot (about 454%) better at AF than the GeForce 8400 GS 512MB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce 8400 GS 512MB		5200 Mtexels/sec
	Difference: 23600 (454%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the GeForce GT 640 DDR3 is the winner, by a large margin. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 8400 GS 512MB		2600 Mpixels/sec
	Difference: 11800 (454%)

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 transported across the external memory interface in one second. It is worked out by multiplying the bus width by the speed of its memory. In the case of DDR type memory, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed in one second. This number is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The higher this number, the better the graphics 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 chip could possibly record to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.