Radeon HD 4790 vs Radeon HD 4890 1GB

Intro

Compare those specifications to the Radeon HD 4890 1GB, which comes with a core clock frequency of 1000 MHz and a GDDR5 memory frequency of 975 MHz. It also features a 256-bit memory bus, and makes use of a 55 nm design. It features 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 4890 1GB should theoretically be much better than the Radeon HD 4790 overall. (explain)

Radeon HD 4890 1GB		124800 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 22400 (22%)

Texel Rate

The Radeon HD 4890 1GB will be much (about 108%) faster with regards to anisotropic filtering than the Radeon HD 4790. (explain)

Radeon HD 4890 1GB		40000 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 20800 (108%)

Pixel Rate

The Radeon HD 4890 1GB is quite a bit (more or less 67%) better at anti-aliasing than the Radeon HD 4790, and also should be capable of handling higher screen resolutions while still performing well. (explain)

Radeon HD 4890 1GB		16000 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 6400 (67%)

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 max amount of information (counted in MB per second) that can be transferred across the external memory interface in a second. It is calculated by multiplying the card's interface width by the speed of its memory. If the card has DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. 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 number of texture map elements (texels) that can be applied per second. This is worked out by multiplying the total amount of texture units by the core speed of the chip. The higher this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly record to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called 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 ability to reach the maximum fill rate.