GeForce 8400 GS 512MB vs Radeon HD 6990

Intro

Compare those specs to the Radeon HD 6990, which comes with a GPU core clock speed of 830 MHz, and 2048 MB of GDDR5 RAM running at 1250 MHz through a 256-bit bus. It also is made up of 1536 SPUs, 96 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8400 GS 512MB		40 Watts
Radeon HD 6990		375 Watts
	Difference: 335 Watts (838%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6990 is 4900% faster than the GeForce 8400 GS 512MB in general, due to its higher bandwidth. (explain)

Radeon HD 6990		320000 MB/sec
GeForce 8400 GS 512MB		6400 MB/sec
	Difference: 313600 (4900%)

Texel Rate

The Radeon HD 6990 is quite a bit (more or less 2965%) better at anisotropic filtering than the GeForce 8400 GS 512MB. (explain)

Radeon HD 6990		159360 Mtexels/sec
GeForce 8400 GS 512MB		5200 Mtexels/sec
	Difference: 154160 (2965%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 6990 is the winner, by far. (explain)

Radeon HD 6990		53120 Mpixels/sec
GeForce 8400 GS 512MB		2600 Mpixels/sec
	Difference: 50520 (1943%)

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 largest amount of data (counted in MB per second) that can be transported across the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory speed. If it uses DDR memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This is calculated 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 a second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly record to its local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.