Radeon HD 4790 vs Radeon HD 4890 2GB

Intro

Compare those specifications to the Radeon HD 4890 2GB, which features a core clock speed of 1000 MHz and a GDDR5 memory frequency of 975 MHz. It also makes use of a 256-bit memory bus, and uses a 55 nm design. It is comprised of 800(160x5) SPUs, 40 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 4890 2GB, in theory, should perform quite a bit faster than the Radeon HD 4790 in general. (explain)

Radeon HD 4890 2GB		124800 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 22400 (22%)

Texel Rate

The Radeon HD 4890 2GB should be a lot (approximately 108%) better at texture filtering than the Radeon HD 4790. (explain)

Radeon HD 4890 2GB		40000 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 20800 (108%)

Pixel Rate

The Radeon HD 4890 2GB will be quite a bit (approximately 67%) more effective at FSAA than the Radeon HD 4790, and also should be able to handle higher resolutions while still performing well. (explain)

Radeon HD 4890 2GB		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 data (counted in MB per second) that can be transferred over the external memory interface within a second. It is worked out by multiplying the card's interface width by its memory clock speed. In the case of DDR type memory, 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 anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied per second. This is worked out by multiplying the total texture units of the card by the core clock speed of the chip. The better this number, the better the graphics 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 chip can possibly write to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes 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.