Radeon HD 4890 2GB vs Radeon HD 6750

Intro

Compare that to the Radeon HD 6750, which comes with a core clock frequency of 725 MHz and a GDDR5 memory frequency of 1000 MHz. It also uses a 128-bit memory bus, and makes use of a 40 nm design. It is made up of 720 SPUs, 36 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6750		86 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 104 Watts (121%)

Memory Bandwidth

The Radeon HD 4890 2GB should theoretically be much faster than the Radeon HD 6750 overall. (explain)

Radeon HD 4890 2GB		124800 MB/sec
Radeon HD 6750		64000 MB/sec
	Difference: 60800 (95%)

Texel Rate

The Radeon HD 4890 2GB is much (more or less 53%) better at anisotropic filtering than the Radeon HD 6750. (explain)

Radeon HD 4890 2GB		40000 Mtexels/sec
Radeon HD 6750		26100 Mtexels/sec
	Difference: 13900 (53%)

Pixel Rate

The Radeon HD 4890 2GB will be much (more or less 38%) faster with regards to FSAA than the Radeon HD 6750, and also should be able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 4890 2GB		16000 Mpixels/sec
Radeon HD 6750		11600 Mpixels/sec
	Difference: 4400 (38%)

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 data (counted in MB per second) that can be transferred across the external memory interface within a second. The number is worked out by multiplying the card's bus width by its memory speed. In the case of DDR type RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's 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 texture map elements (texels) that are applied per second. This is worked out by multiplying the total amount of texture units by the core 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 per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly write to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.