GeForce 9800 GX2 vs Radeon HD 7870

Intro

Compare those specifications to the Radeon HD 7870, which makes use of a 28 nm design. AMD has set the core speed at 1000 MHz. The GDDR5 memory is set to run at a speed of 1200 MHz on this specific card. It features 1280 SPUs along with 80 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7870		175 Watts
GeForce 9800 GX2		197 Watts
	Difference: 22 Watts (13%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7870 should perform a bit faster than the GeForce 9800 GX2 overall. (explain)

Radeon HD 7870		153600 MB/sec
GeForce 9800 GX2		128000 MB/sec
	Difference: 25600 (20%)

Texel Rate

The Radeon HD 7870 is just a bit (more or less 4%) more effective at AF than the GeForce 9800 GX2. (explain)

Radeon HD 7870		80000 Mtexels/sec
GeForce 9800 GX2		76800 Mtexels/sec
	Difference: 3200 (4%)

Pixel Rate

The Radeon HD 7870 should be much (approximately 67%) better at full screen anti-aliasing than the GeForce 9800 GX2, and will be capable of handling higher screen resolutions better. (explain)

Radeon HD 7870		32000 Mpixels/sec
GeForce 9800 GX2		19200 Mpixels/sec
	Difference: 12800 (67%)

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 information (counted in MB per second) that can be transported past the external memory interface in a second. It is worked out by multiplying the card's bus width by its memory speed. In the case of DDR RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, 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 number of texture map elements (texels) that can be applied per second. This number is calculated by multiplying the total texture units by the core clock speed of the chip. The better this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the most pixels the video card can possibly record to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.