GeForce GTX 660 Ti vs Radeon HD 4890 1GB

Intro

Compare all that to the Radeon HD 4890 1GB, which comes with GPU core speed of 1000 MHz, and 1024 MB of GDDR5 memory set to run at 975 MHz through a 256-bit bus. It also is made up of 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 660 Ti		150 Watts
Radeon HD 4890 1GB		190 Watts
	Difference: 40 Watts (27%)

Memory Bandwidth

Theoretically speaking, the GeForce GTX 660 Ti is 15% quicker than the Radeon HD 4890 1GB in general, because of its greater bandwidth. (explain)

GeForce GTX 660 Ti		144000 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 19200 (15%)

Texel Rate

The GeForce GTX 660 Ti should be quite a bit (about 156%) faster with regards to AF than the Radeon HD 4890 1GB. (explain)

GeForce GTX 660 Ti		102480 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 62480 (156%)

Pixel Rate

The GeForce GTX 660 Ti should be a lot (approximately 37%) better at AA than the Radeon HD 4890 1GB, and also able to handle higher resolutions more effectively. (explain)

GeForce GTX 660 Ti		21960 Mpixels/sec
Radeon HD 4890 1GB		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 max amount of data (measured in MB per second) that can be transported across the external memory interface in a second. It is calculated by multiplying the card's bus width by its memory clock speed. If the card has DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher 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 texture map elements (texels) that are processed per second. This number is worked out by multiplying the total number of texture units by the core clock speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.