Radeon HD 4850 2GB vs Radeon HD 6990

Intro

Compare those specs to the Radeon HD 6990, which has a core clock speed of 830 MHz and a GDDR5 memory speed of 1250 MHz. It also features a 256-bit memory bus, and makes use of a 40 nm design. It is comprised of 1536 SPUs, 96 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 2GB		110 Watts
Radeon HD 6990		375 Watts
	Difference: 265 Watts (241%)

Memory Bandwidth

Performance-wise, the Radeon HD 6990 should in theory be quite a bit superior to the Radeon HD 4850 2GB overall. (explain)

Radeon HD 6990		320000 MB/sec
Radeon HD 4850 2GB		63552 MB/sec
	Difference: 256448 (404%)

Texel Rate

The Radeon HD 6990 is quite a bit (about 537%) more effective at AF than the Radeon HD 4850 2GB. (explain)

Radeon HD 6990		159360 Mtexels/sec
Radeon HD 4850 2GB		25000 Mtexels/sec
	Difference: 134360 (537%)

Pixel Rate

The Radeon HD 6990 will be quite a bit (more or less 431%) better at AA than the Radeon HD 4850 2GB, and also will be capable of handling higher screen resolutions without losing too much performance. (explain)

Radeon HD 6990		53120 Mpixels/sec
Radeon HD 4850 2GB		10000 Mpixels/sec
	Difference: 43120 (431%)

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 maximum amount of information (counted in megabytes per second) that can be transferred over the external memory interface within a second. It's worked out by multiplying the bus width by its memory speed. If the card has DDR type memory, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed per second. This is worked out by multiplying the total texture units of the card by the core speed of the chip. The higher the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly write to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.