GeForce 9800 GX2 vs Radeon HD 4790

Intro

Compare those specs to the Radeon HD 4790, which features a core clock speed of 600 MHz and a GDDR5 memory frequency of 800 MHz. It also features a 256-bit memory bus, and uses a 55 nm design. It features 640(128x5) SPUs, 32 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the GeForce 9800 GX2 should perform much faster than the Radeon HD 4790 in general. (explain)

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

Texel Rate

The GeForce 9800 GX2 will be a lot (more or less 300%) faster with regards to texture filtering than the Radeon HD 4790. (explain)

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

Pixel Rate

The GeForce 9800 GX2 is much (approximately 100%) more effective at full screen anti-aliasing than the Radeon HD 4790, and should be capable of handling higher screen resolutions without slowing down too much. (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 maximum amount of information (counted in MB per second) that can be moved across the external memory interface within a second. It's calculated by multiplying the card's interface width by its memory clock speed. In the case of DDR type RAM, it must 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 anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied per second. This figure is worked out by multiplying the total amount of texture units of the card by the core 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 in a second.

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly record to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.