GeForce GTX 660 Ti vs Radeon HD 4890 1GB

Intro

Compare those specifications to the Radeon HD 4890 1GB, which features 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

As far as performance goes, the GeForce GTX 660 Ti should theoretically be a small bit better than the Radeon HD 4890 1GB overall. (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 is much (approximately 156%) better at 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 is much (approximately 37%) more effective at anti-aliasing than the Radeon HD 4890 1GB, and also will be capable of handling higher screen resolutions without losing too much performance. (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 maximum amount of information (measured in megabytes per second) that can be transferred over the external memory interface in a second. It is calculated by multiplying the interface width by its memory clock speed. If it uses DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the 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 amount of texture map elements (texels) that can be processed per second. This figure is worked out by multiplying the total number of texture units of the card by the core speed of the chip. The higher the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly record to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the number of colour ROPs by the the card's 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 also depends on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.