Radeon HD 4850 X2 1GB vs Radeon HD 6990

Intro

Compare those specs to the Radeon HD 6990, which uses a 40 nm design. AMD has clocked the core frequency at 830 MHz. The GDDR5 memory runs at a frequency of 1250 MHz on this particular model. It features 1536 SPUs along with 96 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 X2 1GB		250 Watts
Radeon HD 6990		375 Watts
	Difference: 125 Watts (50%)

Memory Bandwidth

In theory, the Radeon HD 6990 should be 152% quicker than the Radeon HD 4850 X2 1GB in general, because of its greater data rate. (explain)

Radeon HD 6990		320000 MB/sec
Radeon HD 4850 X2 1GB		127104 MB/sec
	Difference: 192896 (152%)

Texel Rate

The Radeon HD 6990 is much (about 219%) better at AF than the Radeon HD 4850 X2 1GB. (explain)

Radeon HD 6990		159360 Mtexels/sec
Radeon HD 4850 X2 1GB		50000 Mtexels/sec
	Difference: 109360 (219%)

Pixel Rate

The Radeon HD 6990 should be much (approximately 166%) more effective at full screen anti-aliasing than the Radeon HD 4850 X2 1GB, and also should be capable of handling higher resolutions while still performing well. (explain)

Radeon HD 6990		53120 Mpixels/sec
Radeon HD 4850 X2 1GB		20000 Mpixels/sec
	Difference: 33120 (166%)

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 data (counted in MB per second) that can be transferred across the external memory interface in one second. The number is calculated by multiplying the interface width by the speed of its memory. If it uses DDR memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied per second. This is calculated by multiplying the total number of texture units of the card 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 per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to the local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the amount of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.