GeForce 9800 GX2 vs Radeon HD 7850

Intro

Compare those specifications to the Radeon HD 7850, which has a core clock speed of 860 MHz and a GDDR5 memory frequency of 1200 MHz. It also uses a 256-bit bus, and uses a 28 nm design. It is made up of 1024 SPUs, 64 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7850		130 Watts
GeForce 9800 GX2		197 Watts
	Difference: 67 Watts (52%)

Memory Bandwidth

In theory, the Radeon HD 7850 should be 20% quicker than the GeForce 9800 GX2 overall, due to its higher bandwidth. (explain)

Radeon HD 7850		153600 MB/sec
GeForce 9800 GX2		128000 MB/sec
	Difference: 25600 (20%)

Texel Rate

The GeForce 9800 GX2 should be quite a bit (about 40%) faster with regards to AF than the Radeon HD 7850. (explain)

GeForce 9800 GX2		76800 Mtexels/sec
Radeon HD 7850		55040 Mtexels/sec
	Difference: 21760 (40%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 7850 is a better choice, by a large margin. (explain)

Radeon HD 7850		27520 Mpixels/sec
GeForce 9800 GX2		19200 Mpixels/sec
	Difference: 8320 (43%)

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 maximum amount of data (measured in MB per second) that can be transported across the external memory interface in a second. It's calculated by multiplying the card's bus width by the speed of its memory. If it uses DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the card's 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 amount of texture map elements (texels) that can be applied per second. This figure 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 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 maximum amount of pixels that the graphics chip could possibly write to the local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.