Radeon HD 4890 2GB vs Radeon HD 6750

Intro

Compare all that to the Radeon HD 6750, which has a core clock speed of 725 MHz and a GDDR5 memory speed 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 Raster Operation Units.

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

Performance-wise, the Radeon HD 4890 2GB should in theory be a lot better 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 quite a bit (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

If using lots of anti-aliasing is important to you, then the Radeon HD 4890 2GB is superior to the Radeon HD 6750, by a large margin. (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 (in units of megabytes per second) that can be transferred across the external memory interface within a second. It is worked out by multiplying the interface width by its memory speed. If the card has DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's 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 amount of texture map elements (texels) that are applied per second. This is worked out by multiplying the total number of texture units by the core clock speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly record to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.