GeForce 9400 GT 256MB vs Geforce GTX 680

Intro

Compare those specs to the Geforce GTX 680, which comes with a clock frequency of 1006 MHz and a GDDR5 memory frequency of 1502 MHz. It also features a 256-bit bus, and makes use of a 28 nm design. It is comprised of 1536 SPUs, 128 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 9400 GT 256MB		50 Watts
Geforce GTX 680		195 Watts
	Difference: 145 Watts (290%)

Memory Bandwidth

In theory, the Geforce GTX 680 should perform a lot faster than the GeForce 9400 GT 256MB overall. (explain)

Geforce GTX 680		192256 MB/sec
GeForce 9400 GT 256MB		12800 MB/sec
	Difference: 179456 (1402%)

Texel Rate

The Geforce GTX 680 is a lot (about 2827%) more effective at AF than the GeForce 9400 GT 256MB. (explain)

Geforce GTX 680		128768 Mtexels/sec
GeForce 9400 GT 256MB		4400 Mtexels/sec
	Difference: 124368 (2827%)

Pixel Rate

The Geforce GTX 680 should be much (more or less 1363%) more effective at AA than the GeForce 9400 GT 256MB, and also should be capable of handling higher screen resolutions without slowing down too much. (explain)

Geforce GTX 680		32192 Mpixels/sec
GeForce 9400 GT 256MB		2200 Mpixels/sec
	Difference: 29992 (1363%)

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: Bandwidth is the max amount of information (measured in megabytes per second) that can be transferred across the external memory interface within a second. It's worked out by multiplying the bus width by its memory speed. If the card has DDR memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This 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 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 most pixels that the graphics chip can possibly record to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Raster Operations Pipelines 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 rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.