Radeon HD 4870 X2 vs Radeon HD 6850

Intro

Compare those specifications to the Radeon HD 6850, which makes use of a 40 nm design. AMD has clocked the core frequency at 775 MHz. The GDDR5 RAM runs at a speed of 1000 MHz on this specific model. It features 960 SPUs along with 48 TAUs and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6850		127 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 223 Watts (176%)

Memory Bandwidth

Performance-wise, the Radeon HD 4870 X2 should theoretically be quite a bit better than the Radeon HD 6850 in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 6850		128000 MB/sec
	Difference: 102400 (80%)

Texel Rate

The Radeon HD 4870 X2 should be quite a bit (about 61%) better at AF than the Radeon HD 6850. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 6850		37200 Mtexels/sec
	Difference: 22800 (61%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 6850 is superior to the Radeon HD 4870 X2, though not by far. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 4870 X2		24000 Mpixels/sec
	Difference: 800 (3%)

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 (counted in megabytes per second) that can be moved across the external memory interface within a second. It's worked out by multiplying the card's interface width by its memory speed. If the card has DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This figure is worked out by multiplying the total texture units 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 number of pixels the video card could possibly record to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.