GeForce GTX 660 Ti vs Radeon HD 4890 1GB

Intro

Compare that to the Radeon HD 4890 1GB, which features a clock speed of 1000 MHz and a GDDR5 memory speed of 975 MHz. It also features a 256-bit bus, and makes use of a 55 nm design. It features 800(160x5) SPUs, 40 TAUs, and 16 ROPs.

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 should be 15% faster than the Radeon HD 4890 1GB in general, due to 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 will be much (approximately 156%) faster with regards to anisotropic filtering 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 anti-aliasing than the Radeon HD 4890 1GB, and will be capable of handling higher screen resolutions without slowing down too much. (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: Bandwidth is the largest amount of information (in units of MB per second) that can be transferred across the external memory interface within a second. The number is worked out by multiplying the bus width by its memory speed. If it uses DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This number is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The better the texel rate, the better the video 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 maximum number of pixels the graphics card could possibly write to the local memory in one 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 - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.