GeForce GTX 660 Ti vs Radeon HD 4890 2GB

Intro

Compare all that to the Radeon HD 4890 2GB, which comes with GPU core speed of 1000 MHz, and 2048 MB of GDDR5 RAM running at 975 MHz through a 256-bit bus. It also features 800(160x5) SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 660 Ti		150 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 40 Watts (27%)

Memory Bandwidth

Theoretically speaking, the GeForce GTX 660 Ti should be 15% faster than the Radeon HD 4890 2GB overall, due to its higher bandwidth. (explain)

GeForce GTX 660 Ti		144000 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 19200 (15%)

Texel Rate

The GeForce GTX 660 Ti is a lot (about 156%) more effective at anisotropic filtering than the Radeon HD 4890 2GB. (explain)

GeForce GTX 660 Ti		102480 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 62480 (156%)

Pixel Rate

If using high levels of AA is important to you, then the GeForce GTX 660 Ti is the winner, by far. (explain)

GeForce GTX 660 Ti		21960 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 5960 (37%)

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 (measured in MB per second) that can be moved across the external memory interface in a second. The number is worked out by multiplying the card's bus width by its memory clock speed. If it uses DDR RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better 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 are processed per second. This number is calculated 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 texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the most pixels 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 card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.