GeForce 8600 GT 512MB DDR2 vs Radeon HD 4790

Intro

Compare those specs to the Radeon HD 4790, which comes with core 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 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 4790 should be 700% faster than the GeForce 8600 GT 512MB DDR2 in general, because of its greater bandwidth. (explain)

Radeon HD 4790		102400 MB/sec
GeForce 8600 GT 512MB DDR2		12800 MB/sec
	Difference: 89600 (700%)

Texel Rate

The Radeon HD 4790 should be quite a bit (approximately 122%) better at AF than the GeForce 8600 GT 512MB DDR2. (explain)

Radeon HD 4790		19200 Mtexels/sec
GeForce 8600 GT 512MB DDR2		8640 Mtexels/sec
	Difference: 10560 (122%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 4790 is the winner, by far. (explain)

Radeon HD 4790		9600 Mpixels/sec
GeForce 8600 GT 512MB DDR2		4320 Mpixels/sec
	Difference: 5280 (122%)

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.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the maximum amount of information (in units of MB per second) that can be transferred across the external memory interface in a second. It's worked out by multiplying the bus width by its memory speed. If the card has DDR type memory, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range 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 calculated by multiplying the total number of texture units by the core 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 a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly write to the local memory per 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 - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel 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 max fill rate.