GeForce GTX 980 vs Radeon HD 4890 2GB

Intro

Compare that to the Radeon HD 4890 2GB, which comes with a core clock frequency of 1000 MHz and a GDDR5 memory speed of 975 MHz. It also features a 256-bit memory bus, and makes use of a 55 nm design. It is comprised of 800(160x5) SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 980		165 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 25 Watts (15%)

Memory Bandwidth

Theoretically, the GeForce GTX 980 should be much faster than the Radeon HD 4890 2GB overall. (explain)

GeForce GTX 980		224000 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 99200 (79%)

Texel Rate

The GeForce GTX 980 should be much (about 260%) more effective at AF than the Radeon HD 4890 2GB. (explain)

GeForce GTX 980		144128 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 104128 (260%)

Pixel Rate

The GeForce GTX 980 is much (about 350%) better at FSAA than the Radeon HD 4890 2GB, and also will be able to handle higher screen resolutions better. (explain)

GeForce GTX 980		72064 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 56064 (350%)

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: Bandwidth is the maximum amount of information (measured in megabytes per second) that can be transported over the external memory interface within a second. The number is calculated by multiplying the card's interface width by its memory clock speed. If it uses DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed per second. This number is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The better this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant 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 get to the maximum fill rate.