GeForce 9800 GX2 vs Radeon HD 4870 512MB

Intro

Compare all that to the Radeon HD 4870 512MB, which has a core clock frequency of 750 MHz and a GDDR5 memory frequency of 900 MHz. It also features a 256-bit memory bus, and uses a 55 nm design. It is comprised of 800(160x5) SPUs, 40 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 512MB		150 Watts
GeForce 9800 GX2		197 Watts
	Difference: 47 Watts (31%)

Memory Bandwidth

Theoretically speaking, the GeForce 9800 GX2 should be a little bit faster than the Radeon HD 4870 512MB overall. (explain)

GeForce 9800 GX2		128000 MB/sec
Radeon HD 4870 512MB		115200 MB/sec
	Difference: 12800 (11%)

Texel Rate

The GeForce 9800 GX2 will be much (more or less 156%) faster with regards to texture filtering than the Radeon HD 4870 512MB. (explain)

GeForce 9800 GX2		76800 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 46800 (156%)

Pixel Rate

If using a high resolution is important to you, then the GeForce 9800 GX2 is a better choice, by a large margin. (explain)

GeForce 9800 GX2		19200 Mpixels/sec
Radeon HD 4870 512MB		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: Memory bandwidth is the max amount of data (counted in megabytes per second) that can be moved across the external memory interface in one second. It's worked out by multiplying the card's interface width by the speed of its memory. In the case of DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, 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 worked out by multiplying the total texture units of the card by the core clock speed of the chip. The higher this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as 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 memory bandwidth is, the lower the ability to reach the maximum fill rate.