GeForce GTX 660 vs Radeon HD 4890 2GB

Intro

Compare all of that to the Radeon HD 4890 2GB, which uses a 55 nm design. AMD has set the core speed at 1000 MHz. The GDDR5 memory runs at a frequency of 975 MHz on this model. It features 800(160x5) SPUs along with 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 660		140 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 50 Watts (36%)

Memory Bandwidth

Theoretically, the GeForce GTX 660 should be just a bit faster than the Radeon HD 4890 2GB in general. (explain)

GeForce GTX 660		144192 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 19392 (16%)

Texel Rate

The GeForce GTX 660 will be much (about 96%) faster with regards to texture filtering than the Radeon HD 4890 2GB. (explain)

GeForce GTX 660		78400 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 38400 (96%)

Pixel Rate

If running with a high resolution is important to you, then the GeForce GTX 660 is the winner, by far. (explain)

GeForce GTX 660		23520 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 7520 (47%)

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 data (in units of MB per second) that can be transferred over the external memory interface in a second. The number is calculated by multiplying the card's bus width by its memory speed. If it uses DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This 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 graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.