GeForce GT 640 DDR3 vs GeForce GTX 295

Intro

Compare those specifications to the GeForce GTX 295, which makes use of a 55 nm design. nVidia has set the core speed at 576 MHz. The GDDR3 RAM works at a speed of 999 MHz on this specific card. It features 240 SPUs as well as 80 Texture Address Units and 28 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce GTX 295		289 Watts
	Difference: 224 Watts (345%)

Memory Bandwidth

In theory, the GeForce GTX 295 is 292% faster than the GeForce GT 640 DDR3 in general, due to its greater bandwidth. (explain)

GeForce GTX 295		223776 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 166752 (292%)

Texel Rate

The GeForce GTX 295 should be quite a bit (about 220%) faster with regards to AF than the GeForce GT 640 DDR3. (explain)

GeForce GTX 295		92160 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 63360 (220%)

Pixel Rate

The GeForce GTX 295 should be much (about 124%) better at full screen anti-aliasing than the GeForce GT 640 DDR3, and will be capable of handling higher resolutions better. (explain)

GeForce GTX 295		32256 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 17856 (124%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the max amount of information (in units of MB per second) that can be transferred past the external memory interface in one second. It's calculated by multiplying the bus width by its memory speed. In the case of DDR type RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, 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 texture map elements (texels) that can be processed 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 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 chip could possibly write to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.