GeForce 9800 GX2 vs Radeon HD 4790

Intro

Compare all of that to the Radeon HD 4790, which comes with clock speeds of 600 MHz on the GPU, and 800 MHz on the 512 MB of GDDR5 memory. It features 640(128x5) SPUs along with 32 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the GeForce 9800 GX2 should theoretically be a lot better than the Radeon HD 4790 overall. (explain)

GeForce 9800 GX2		128000 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 25600 (25%)

Texel Rate

The GeForce 9800 GX2 should be a lot (approximately 300%) more effective at anisotropic filtering than the Radeon HD 4790. (explain)

GeForce 9800 GX2		76800 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 57600 (300%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the GeForce 9800 GX2 is a better choice, and very much so. (explain)

GeForce 9800 GX2		19200 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 9600 (100%)

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 largest amount of data (counted in megabytes per second) that can be moved across the external memory interface within a second. It's worked out by multiplying the card's bus width by the speed of its memory. In the case of DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied in one second. This figure is calculated by multiplying the total amount of 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 can possibly record to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.