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GeForce GT 640 DDR3 vs GeForce GTX 460

Intro

The GeForce GT 640 DDR3 has a GPU core speed of 900 MHz, and the 2048 MB of DDR3 memory is set to run at 1782 MHz through a 128-bit bus. It also features 384 SPUs, 32 Texture Address Units, and 16 Raster Operation Units.

Compare those specs to the GeForce GTX 460, which has a GPU core clock speed of 675 MHz, and 768 MB of GDDR5 RAM running at 900 MHz through a 192-bit bus. It also features 336 SPUs, 56 TAUs, and 24 ROPs.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3 65 Watts
GeForce GTX 460 150 Watts
Difference: 85 Watts (131%)

Memory Bandwidth

As far as performance goes, the GeForce GTX 460 should theoretically be quite a bit superior to the GeForce GT 640 DDR3 in general. (explain)

GeForce GTX 460 86400 MB/sec
GeForce GT 640 DDR3 57024 MB/sec
Difference: 29376 (52%)

Texel Rate

The GeForce GTX 460 will be quite a bit (about 31%) faster with regards to AF than the GeForce GT 640 DDR3. (explain)

GeForce GTX 460 37800 Mtexels/sec
GeForce GT 640 DDR3 28800 Mtexels/sec
Difference: 9000 (31%)

Pixel Rate

The GeForce GTX 460 will be a little bit (approximately 13%) more effective at FSAA than the GeForce GT 640 DDR3, and also will be capable of handling higher resolutions while still performing well. (explain)

GeForce GTX 460 16200 Mpixels/sec
GeForce GT 640 DDR3 14400 Mpixels/sec
Difference: 1800 (13%)

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

GeForce GT 640 DDR3

Amazon.com

GeForce GTX 460

Amazon.com

Please note that the price comparisons are based on search keywords - sometimes it might show cards with very similar names that are not exactly the same as the one chosen in the comparison. We do try to filter out the wrong results as best we can, though.

Specifications

Model GeForce GT 640 DDR3 GeForce GTX 460
Manufacturer nVidia nVidia
Year June 2012 July 2010
Code Name GK107 GF104
Fab Process 28 nm 40 nm
Bus PCIe 3.0 x16 PCIe x16
Memory 2048 MB 768 MB
Core Speed 900 MHz 675 MHz
Shader Speed 900 MHz 1350 MHz
Memory Speed 1782 MHz (3564 MHz effective) 900 MHz (3600 MHz effective)
Unified Shaders 384 336
Texture Mapping Units 32 56
Render Output Units 16 24
Bus Type DDR3 GDDR5
Bus Width 128-bit 192-bit
DirectX Version DirectX 11.0 DirectX 11
OpenGL Version OpenGL 4.2 OpenGL 4.1
Power (Max TDP) 65 watts 150 watts
Shader Model 5.0 5.0
Bandwidth 57024 MB/sec 86400 MB/sec
Texel Rate 28800 Mtexels/sec 37800 Mtexels/sec
Pixel Rate 14400 Mpixels/sec 16200 Mpixels/sec

Memory Bandwidth: Bandwidth is the largest amount of information (in units of megabytes per second) that can be transferred past the external memory interface in a second. It's worked out by multiplying the bus width by its memory clock speed. If it uses DDR RAM, it must be multiplied by 2 again. If it uses 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 number of texture map elements (texels) that are processed per second. This number is calculated by multiplying the total texture units of the card by the core speed of the chip. The better this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly write to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.

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