GeForce 9800 GX2 vs Radeon HD 6850

Intro

Compare those specs to the Radeon HD 6850, which has GPU clock speed of 775 MHz, and 1024 MB of GDDR5 memory set to run at 1000 MHz through a 256-bit bus. It also is comprised of 960 Stream Processors, 48 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6850		127 Watts
GeForce 9800 GX2		197 Watts
	Difference: 70 Watts (55%)

Memory Bandwidth

Both cards have exactly the same memory bandwidth, so theoretically they should perform the same. (explain)

Texel Rate

The GeForce 9800 GX2 will be quite a bit (approximately 106%) faster with regards to AF than the Radeon HD 6850. (explain)

GeForce 9800 GX2		76800 Mtexels/sec
Radeon HD 6850		37200 Mtexels/sec
	Difference: 39600 (106%)

Pixel Rate

The Radeon HD 6850 should be a lot (approximately 29%) better at FSAA than the GeForce 9800 GX2, and will be capable of handling higher resolutions without losing too much performance. (explain)

Radeon HD 6850		24800 Mpixels/sec
GeForce 9800 GX2		19200 Mpixels/sec
	Difference: 5600 (29%)

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 largest amount of information (measured in megabytes per second) that can be transported over the external memory interface within a second. It is calculated by multiplying the card's interface width by its memory speed. If it uses DDR type memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card can possibly record to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as 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, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.