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GeForce GT 640 DDR3 vs GeForce GTX 650 Ti 2GB

Intro

The GeForce GT 640 DDR3 makes use of a 28 nm design. nVidia has clocked the core frequency at 900 MHz. The DDR3 RAM runs at a speed of 1782 MHz on this particular card. It features 384 SPUs along with 32 Texture Address Units and 16 Rasterization Operator Units.

Compare those specifications to the GeForce GTX 650 Ti 2GB, which has a clock frequency of 928 MHz and a GDDR5 memory speed of 1350 MHz. It also features a 128-bit bus, and uses a 28 nm design. It is comprised of 768 SPUs, 64 TAUs, and 16 Raster Operation 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 650 Ti 2GB 110 Watts
Difference: 45 Watts (69%)

Memory Bandwidth

The GeForce GTX 650 Ti 2GB, in theory, should be a lot faster than the GeForce GT 640 DDR3 overall. (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 quite a bit (more or less 106%) faster with regards to anisotropic filtering 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

The GeForce GTX 650 Ti 2GB is just a bit (about 3%) more effective at anti-aliasing than the GeForce GT 640 DDR3, and also able to handle higher screen resolutions without losing too much performance. (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 (in units of megabytes per second) that can be moved over the external memory interface within a second. It is calculated by multiplying the bus width by its memory clock speed. If it uses DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This is calculated by multiplying the total texture units by the core clock speed of the chip. The better the texel rate, 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 maximum amount of pixels that the graphics card can possibly record to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.

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