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GeForce GT 640 DDR3 vs GeForce GTX 650 Ti 2GB

Intro

The GeForce GT 640 DDR3 has clock speeds of 900 MHz on the GPU, and 1782 MHz on the 2048 MB of DDR3 RAM. It features 384 SPUs as well as 32 Texture Address Units and 16 Rasterization Operator Units.

Compare those specifications to the GeForce GTX 650 Ti 2GB, which has a GPU core clock speed of 928 MHz, and 2048 MB of GDDR5 memory set to run at 1350 MHz through a 128-bit bus. It also is made up of 768 SPUs, 64 Texture Address Units, and 16 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 650 Ti 2GB 110 Watts
Difference: 45 Watts (69%)

Memory Bandwidth

In theory, the GeForce GTX 650 Ti 2GB is 52% faster than the GeForce GT 640 DDR3 overall, due to its greater data rate. (explain)

GeForce GTX 650 Ti 2GB 86400 MB/sec
GeForce GT 640 DDR3 57024 MB/sec
Difference: 29376 (52%)

Texel Rate

The GeForce GTX 650 Ti 2GB should be a lot (more or less 106%) faster with regards to AF than the GeForce GT 640 DDR3. (explain)

GeForce GTX 650 Ti 2GB 59392 Mtexels/sec
GeForce GT 640 DDR3 28800 Mtexels/sec
Difference: 30592 (106%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the GeForce GTX 650 Ti 2GB is a better choice, but not by far. (explain)

GeForce GTX 650 Ti 2GB 14848 Mpixels/sec
GeForce GT 640 DDR3 14400 Mpixels/sec
Difference: 448 (3%)

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 650 Ti 2GB

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 650 Ti 2GB
Manufacturer nVidia nVidia
Year June 2012 October 2012
Code Name GK107 GK106
Fab Process 28 nm 28 nm
Bus PCIe 3.0 x16 PCIe 3.0 x16
Memory 2048 MB 2048 MB
Core Speed 900 MHz 928 MHz
Shader Speed 900 MHz 928 MHz
Memory Speed 1782 MHz (3564 MHz effective) 1350 MHz (5400 MHz effective)
Unified Shaders 384 768
Texture Mapping Units 32 64
Render Output Units 16 16
Bus Type DDR3 GDDR5
Bus Width 128-bit 128-bit
DirectX Version DirectX 11.0 DirectX 11.0
OpenGL Version OpenGL 4.2 OpenGL 4.3
Power (Max TDP) 65 watts 110 watts
Shader Model 5.0 5.0
Bandwidth 57024 MB/sec 86400 MB/sec
Texel Rate 28800 Mtexels/sec 59392 Mtexels/sec
Pixel Rate 14400 Mpixels/sec 14848 Mpixels/sec

Memory Bandwidth: Bandwidth is the max amount of information (counted in MB per second) that can be transported past the external memory interface within a second. It is calculated by multiplying the card's bus width by the speed of its memory. If the card has DDR type RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed per second. This number is worked out by multiplying the total number of texture units by the core speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly record to its local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.

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