Radeon HD 4850 X2 1GB vs Radeon HD 6950 2GB

Intro

Compare those specifications to the Radeon HD 6950 2GB, which features GPU clock speed of 800 MHz, and 2048 MB of GDDR5 RAM set to run at 1250 MHz through a 256-bit bus. It also is comprised of 1408 Stream Processors, 88 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 6950 2GB		200 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 50 Watts (25%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6950 2GB is 26% quicker than the Radeon HD 4850 X2 1GB overall, because of its greater bandwidth. (explain)

Radeon HD 6950 2GB		160000 MB/sec
Radeon HD 4850 X2 1GB		127104 MB/sec
	Difference: 32896 (26%)

Texel Rate

The Radeon HD 6950 2GB is much (approximately 41%) faster with regards to AF than the Radeon HD 4850 X2 1GB. (explain)

Radeon HD 6950 2GB		70400 Mtexels/sec
Radeon HD 4850 X2 1GB		50000 Mtexels/sec
	Difference: 20400 (41%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 6950 2GB is the winner, and very much so. (explain)

Radeon HD 6950 2GB		25600 Mpixels/sec
Radeon HD 4850 X2 1GB		20000 Mpixels/sec
	Difference: 5600 (28%)

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: Memory bandwidth is the max amount of information (in units of MB per second) that can be moved across the external memory interface within a second. It is worked out by multiplying the interface width by the speed of its memory. If the card has DDR RAM, it must be multiplied by 2 once 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 can be applied per second. This figure is worked out by multiplying the total texture units by the core clock speed of the chip. The better the texel rate, 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 chip can possibly record to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.