GeForce 9800 GX2 vs Radeon HD 7990

Intro

Compare all that to the Radeon HD 7990, which comes with a clock speed of 950 MHz and a GDDR5 memory speed of 1500 MHz. It also features a 384-bit memory bus, and makes use of a 28 nm design. It is comprised of 2048 SPUs, 128 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 9800 GX2		197 Watts
Radeon HD 7990		375 Watts
	Difference: 178 Watts (90%)

Memory Bandwidth

In theory, the Radeon HD 7990 is 350% faster than the GeForce 9800 GX2 overall, due to its higher bandwidth. (explain)

Radeon HD 7990		576000 MB/sec
GeForce 9800 GX2		128000 MB/sec
	Difference: 448000 (350%)

Texel Rate

The Radeon HD 7990 should be a lot (about 217%) more effective at AF than the GeForce 9800 GX2. (explain)

Radeon HD 7990		243200 Mtexels/sec
GeForce 9800 GX2		76800 Mtexels/sec
	Difference: 166400 (217%)

Pixel Rate

The Radeon HD 7990 should be quite a bit (about 217%) faster with regards to anti-aliasing than the GeForce 9800 GX2, and will be able to handle higher screen resolutions more effectively. (explain)

Radeon HD 7990		60800 Mpixels/sec
GeForce 9800 GX2		19200 Mpixels/sec
	Difference: 41600 (217%)

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 largest amount of data (counted in megabytes per second) that can be transported across the external memory interface in one second. It is calculated by multiplying the bus width by its memory clock speed. If it uses DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This number is worked out by multiplying the total texture units by the core 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 processed per second.

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly write to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.