GeForce 8400 GS 512MB vs GeForce 9800 GX2

Intro

Compare those specs to the GeForce 9800 GX2, which features core speeds of 600 MHz on the GPU, and 1000 MHz on the 512 MB of GDDR3 RAM. It features 128 SPUs along with 64 Texture Address Units and 16 Rasterization Operator Units.

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

The GeForce 9800 GX2 should in theory be a lot faster than the GeForce 8400 GS 512MB overall. (explain)

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

Texel Rate

The GeForce 9800 GX2 is quite a bit (approximately 1377%) better at AF 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 lots of anti-aliasing is important to you, then the GeForce 9800 GX2 is a better choice, 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 max amount of data (counted in MB per second) that can be transported across the external memory interface in one second. It is worked out by multiplying the card's bus width by the speed of its memory. In the case of DDR memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This number is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The better this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly write to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of ROPs 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 output rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.