GeForce 8400 GS 512MB vs GeForce 9800 GX2

Intro

Compare all that to the GeForce 9800 GX2, which has GPU clock speed of 600 MHz, and 512 MB of GDDR3 RAM set to run at 1000 MHz through a 256-bit bus. It also features 128 Stream Processors, 64 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8400 GS 512MB		40 Watts
GeForce 9800 GX2		197 Watts
	Difference: 157 Watts (393%)

Memory Bandwidth

Theoretically speaking, the GeForce 9800 GX2 is 1900% quicker than the GeForce 8400 GS 512MB overall, because of its greater bandwidth. (explain)

GeForce 9800 GX2		128000 MB/sec
GeForce 8400 GS 512MB		6400 MB/sec
	Difference: 121600 (1900%)

Texel Rate

The GeForce 9800 GX2 will be quite a bit (more or less 1377%) more effective at texture filtering than the GeForce 8400 GS 512MB. (explain)

GeForce 9800 GX2		76800 Mtexels/sec
GeForce 8400 GS 512MB		5200 Mtexels/sec
	Difference: 71600 (1377%)

Pixel Rate

If using a high screen resolution is important to you, then the GeForce 9800 GX2 is the winner, and very much so. (explain)

GeForce 9800 GX2		19200 Mpixels/sec
GeForce 8400 GS 512MB		2600 Mpixels/sec
	Difference: 16600 (638%)

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 megabytes per second) that can be transferred over the external memory interface in a second. It is calculated by multiplying the interface width by its memory speed. If it uses DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the 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 can be applied in one second. This number is worked out by multiplying the total 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 texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called 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 of the card - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.