Radeon HD 6750 vs Radeon HD 6990

Intro

Compare those specifications to the Radeon HD 6990, which makes use of a 40 nm design. AMD has clocked the core frequency at 830 MHz. The GDDR5 RAM is set to run at a speed of 1250 MHz on this particular model. It features 1536 SPUs along with 96 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6750		86 Watts
Radeon HD 6990		375 Watts
	Difference: 289 Watts (336%)

Memory Bandwidth

In theory, the Radeon HD 6990 should be much faster than the Radeon HD 6750 overall. (explain)

Radeon HD 6990		320000 MB/sec
Radeon HD 6750		64000 MB/sec
	Difference: 256000 (400%)

Texel Rate

The Radeon HD 6990 is a lot (about 511%) better at AF than the Radeon HD 6750. (explain)

Radeon HD 6990		159360 Mtexels/sec
Radeon HD 6750		26100 Mtexels/sec
	Difference: 133260 (511%)

Pixel Rate

The Radeon HD 6990 should be much (more or less 358%) more effective at full screen anti-aliasing than the Radeon HD 6750, and also will be capable of handling higher resolutions better. (explain)

Radeon HD 6990		53120 Mpixels/sec
Radeon HD 6750		11600 Mpixels/sec
	Difference: 41520 (358%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the max amount of data (in units of MB per second) that can be moved across the external memory interface within a second. The number is worked out by multiplying the card's bus width by its memory speed. If it uses DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This figure is worked out by multiplying the total amount of texture units by the core speed of the chip. The higher the texel rate, the better the 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 amount of pixels that the graphics card could possibly write to the local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.