GeForce GT 640 DDR3 vs Geforce GTX 680

Intro

Compare all of that to the Geforce GTX 680, which uses a 28 nm design. nVidia has clocked the core speed at 1006 MHz. The GDDR5 RAM runs at a speed of 1502 MHz on this specific card. It features 1536 SPUs as well as 128 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Benchmarks

These are real-world performance benchmarks that were submitted by Hardware Compare users. The scores seen here are the average of all benchmarks submitted for each respective test and hardware.

3DMark Fire Strike Graphics Score

Geforce GTX 680		7650 points
GeForce GT 640 DDR3		1560 points
	Difference: 6090 (390%)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Geforce GTX 680		195 Watts
	Difference: 130 Watts (200%)

Memory Bandwidth

The Geforce GTX 680 should in theory perform much faster than the GeForce GT 640 DDR3 in general. (explain)

Geforce GTX 680		192256 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 135232 (237%)

Texel Rate

The Geforce GTX 680 should be a lot (approximately 347%) faster with regards to anisotropic filtering than the GeForce GT 640 DDR3. (explain)

Geforce GTX 680		128768 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 99968 (347%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Geforce GTX 680 is the winner, and very much so. (explain)

Geforce GTX 680		32192 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 17792 (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.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the maximum amount of information (in units of MB per second) that can be transferred past the external memory interface in a second. The number is calculated by multiplying the interface width by its memory clock speed. In the case of DDR memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the 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 amount of texture map elements (texels) that can be processed in one 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 texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of ROPs by the the core 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 also depends 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.