GeForce 8400 GS 512MB vs GeForce 9800 GX2

Intro

Compare those specifications to the GeForce 9800 GX2, which has GPU core speed of 600 MHz, and 512 MB of GDDR3 memory running at 1000 MHz through a 256-bit bus. It also features 128 SPUs, 64 TAUs, and 16 Raster Operation 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, in theory, should be much 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%) faster with regards to 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 high levels of AA is important to you, then the GeForce 9800 GX2 is superior to the GeForce 8400 GS 512MB, by a large margin. (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: Memory bandwidth is the max amount of data (measured in megabytes per second) that can be transported past the external memory interface in a second. The number is worked out by multiplying the interface width by the speed of its memory. In the case of DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Render Output Units by the the card's clock speed. 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 also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.