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GeForce GT 640 DDR3 vs GeForce GTX 650 Ti 2GB

Intro

The GeForce GT 640 DDR3 has a GPU core clock speed of 900 MHz, and the 2048 MB of DDR3 memory runs at 1782 MHz through a 128-bit bus. It also is made up of 384 Stream Processors, 32 TAUs, and 16 Raster Operation Units.

Compare those specifications to the GeForce GTX 650 Ti 2GB, which uses a 28 nm design. nVidia has set the core frequency at 928 MHz. The GDDR5 RAM works at a speed of 1350 MHz on this specific card. It features 768 SPUs as well as 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

As far as performance goes, the GeForce GTX 650 Ti 2GB should theoretically be a lot superior to the GeForce GT 640 DDR3 in general. (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 will be a lot (about 106%) more effective at 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

The GeForce GTX 650 Ti 2GB will be a small bit (approximately 3%) faster with regards to anti-aliasing than the GeForce GT 640 DDR3, and also will be able to handle higher resolutions without slowing down too much. (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 largest amount of data (measured in megabytes per second) that can be transferred past the external memory interface in a second. The number is worked out by multiplying the bus width by its memory clock speed. In the case of DDR RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, 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 applied per second. This number is worked out 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 card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most pixels the video card 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 Render Output Units by the the core 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 output rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.

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