Geforce GTX 680 vs Radeon HD 4890 2GB

Intro

Compare all of that to the Radeon HD 4890 2GB, which has core clock speeds of 1000 MHz on the GPU, and 975 MHz on the 2048 MB of GDDR5 memory. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4890 2GB		190 Watts
Geforce GTX 680		195 Watts
	Difference: 5 Watts (3%)

Memory Bandwidth

The Geforce GTX 680 should theoretically be quite a bit faster than the Radeon HD 4890 2GB overall. (explain)

Geforce GTX 680		192256 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 67456 (54%)

Texel Rate

The Geforce GTX 680 should be a lot (more or less 222%) better at AF than the Radeon HD 4890 2GB. (explain)

Geforce GTX 680		128768 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 88768 (222%)

Pixel Rate

The Geforce GTX 680 is quite a bit (more or less 101%) faster with regards to FSAA than the Radeon HD 4890 2GB, and also capable of handling higher screen resolutions more effectively. (explain)

Geforce GTX 680		32192 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 16192 (101%)

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 largest amount of information (in units of megabytes per second) that can be transported past the external memory interface within a second. It's calculated by multiplying the interface width by its memory clock speed. If it uses DDR memory, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one second. This is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, 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 most pixels that the graphics card can possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.