Radeon HD 4850 X2 1GB vs Radeon HD 7870 XT

Intro

Compare all that to the Radeon HD 7870 XT, which makes use of a 28 nm design. AMD has set the core speed at 925 MHz. The GDDR5 memory is set to run at a speed of 1500 MHz on this specific model. It features 1536 SPUs as well as 96 TAUs and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7870 XT		185 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 65 Watts (35%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7870 XT is 51% faster than the Radeon HD 4850 X2 1GB overall, because of its greater bandwidth. (explain)

Radeon HD 7870 XT		192000 MB/sec
Radeon HD 4850 X2 1GB		127104 MB/sec
	Difference: 64896 (51%)

Texel Rate

The Radeon HD 7870 XT should be a lot (approximately 78%) more effective at texture filtering than the Radeon HD 4850 X2 1GB. (explain)

Radeon HD 7870 XT		88800 Mtexels/sec
Radeon HD 4850 X2 1GB		50000 Mtexels/sec
	Difference: 38800 (78%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon HD 7870 XT is superior to the Radeon HD 4850 X2 1GB, and very much so. (explain)

Radeon HD 7870 XT		29600 Mpixels/sec
Radeon HD 4850 X2 1GB		20000 Mpixels/sec
	Difference: 9600 (48%)

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 in a second. It is calculated by multiplying the card's interface width by its memory clock speed. If it uses DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This number is worked out by multiplying the total texture units by the core 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 per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of colour ROPs by the the core 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 fill 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 maximum fill rate.