GeForce 9800 GX2 vs Radeon HD 4870 1GB

Intro

Compare all of that to the Radeon HD 4870 1GB, which features a core clock frequency of 750 MHz and a GDDR5 memory speed of 900 MHz. It also makes use of a 256-bit memory bus, and makes use of a 55 nm design. It is made up of 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 1GB		150 Watts
GeForce 9800 GX2		197 Watts
	Difference: 47 Watts (31%)

Memory Bandwidth

In theory, the GeForce 9800 GX2 should be 11% faster than the Radeon HD 4870 1GB in general, because of its higher data rate. (explain)

GeForce 9800 GX2		128000 MB/sec
Radeon HD 4870 1GB		115200 MB/sec
	Difference: 12800 (11%)

Texel Rate

The GeForce 9800 GX2 will be quite a bit (more or less 156%) faster with regards to anisotropic filtering than the Radeon HD 4870 1GB. (explain)

GeForce 9800 GX2		76800 Mtexels/sec
Radeon HD 4870 1GB		30000 Mtexels/sec
	Difference: 46800 (156%)

Pixel Rate

The GeForce 9800 GX2 should be a lot (about 60%) better at anti-aliasing than the Radeon HD 4870 1GB, and also will be capable of handling higher resolutions without slowing down too much. (explain)

GeForce 9800 GX2		19200 Mpixels/sec
Radeon HD 4870 1GB		12000 Mpixels/sec
	Difference: 7200 (60%)

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 max amount of data (counted in MB per second) that can be moved across the external memory interface in one second. It's worked out by multiplying the interface width by its memory clock speed. If it uses DDR RAM, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write 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 clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.