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GeForce GT 640 DDR3 vs GeForce GTX 460

Intro

The GeForce GT 640 DDR3 uses a 28 nm design. nVidia has set the core speed at 900 MHz. The DDR3 memory is set to run at a speed of 1782 MHz on this specific model. It features 384 SPUs as well as 32 TAUs and 16 Rasterization Operator Units.

Compare all that to the GeForce GTX 460, which features a clock frequency of 675 MHz and a GDDR5 memory frequency of 900 MHz. It also makes use of a 192-bit bus, and makes use of a 40 nm design. It is comprised of 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

In theory, the GeForce GTX 460 should perform much faster than the GeForce GT 640 DDR3 overall. (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 much (more or less 31%) faster with regards to texture filtering 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 should be a bit (approximately 13%) faster with regards to AA than the GeForce GT 640 DDR3, and also will be able to handle higher resolutions better. (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 data (counted in megabytes per second) that can be transported past the external memory interface within a second. It's calculated by multiplying the card's interface width by the speed of its memory. If it uses DDR type RAM, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of 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 higher the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly write to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.

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