GeForce 9800 GX2 vs Radeon HD 4890 2GB

Intro

Compare all that to the Radeon HD 4890 2GB, which comes with GPU core speed of 1000 MHz, and 2048 MB of GDDR5 memory set to run at 975 MHz through a 256-bit bus. It also is comprised of 800(160x5) Stream Processors, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4890 2GB		190 Watts
GeForce 9800 GX2		197 Watts
	Difference: 7 Watts (4%)

Memory Bandwidth

In theory, the GeForce 9800 GX2 will be 3% faster than the Radeon HD 4890 2GB in general, because of its higher bandwidth. (explain)

GeForce 9800 GX2		128000 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 3200 (3%)

Texel Rate

The GeForce 9800 GX2 should be a lot (approximately 92%) more effective at AF than the Radeon HD 4890 2GB. (explain)

GeForce 9800 GX2		76800 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 36800 (92%)

Pixel Rate

The GeForce 9800 GX2 will be a bit (more or less 20%) more effective at AA than the Radeon HD 4890 2GB, and should be capable of handling higher screen resolutions better. (explain)

GeForce 9800 GX2		19200 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 3200 (20%)

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 information (measured in megabytes per second) that can be transferred across the external memory interface in one second. It is worked out by multiplying the interface width by its memory clock speed. If it uses DDR memory, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Raster Operations Pipelines by the the core speed of the card. 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, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.