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GeForce GT 640 DDR3 vs GeForce GTX 460

Intro

The GeForce GT 640 DDR3 has a core clock frequency of 900 MHz and a DDR3 memory frequency of 1782 MHz. It also features a 128-bit bus, and uses a 28 nm design. It features 384 SPUs, 32 Texture Address Units, and 16 ROPs.

Compare those specs to the GeForce GTX 460, which has core speeds of 675 MHz on the GPU, and 900 MHz on the 768 MB of GDDR5 memory. It features 336 SPUs along with 56 Texture Address Units and 24 Rasterization Operator Units.

(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 a lot (approximately 31%) faster with regards to anisotropic 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

If running with high levels of AA is important to you, then the GeForce GTX 460 is the winner, but not by far. (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 max amount of data (in units of megabytes per second) that can be transported over the external memory interface in one second. It's calculated by multiplying the bus width by the speed of its memory. If the card has DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher 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 amount of texture map elements (texels) that are applied per second. This is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the most pixels the video card could possibly record to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the core speed of the card. 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 fill rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.

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