Radeon HD 4850 X2 512MB vs Radeon HD 7870 XT

Intro

Compare that to the Radeon HD 7870 XT, which makes use of a 28 nm design. AMD has clocked the core speed at 925 MHz. The GDDR5 memory is set to run at a frequency of 1500 MHz on this particular model. It features 1536 SPUs as well as 96 Texture Address Units 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 512MB		250 Watts
	Difference: 65 Watts (35%)

Memory Bandwidth

Performance-wise, the Radeon HD 7870 XT should in theory be quite a bit better than the Radeon HD 4850 X2 512MB in general. (explain)

Radeon HD 7870 XT		192000 MB/sec
Radeon HD 4850 X2 512MB		127104 MB/sec
	Difference: 64896 (51%)

Texel Rate

The Radeon HD 7870 XT will be a lot (about 78%) more effective at texture filtering than the Radeon HD 4850 X2 512MB. (explain)

Radeon HD 7870 XT		88800 Mtexels/sec
Radeon HD 4850 X2 512MB		50000 Mtexels/sec
	Difference: 38800 (78%)

Pixel Rate

The Radeon HD 7870 XT is quite a bit (more or less 48%) faster with regards to FSAA than the Radeon HD 4850 X2 512MB, and also capable of handling higher screen resolutions without slowing down too much. (explain)

Radeon HD 7870 XT		29600 Mpixels/sec
Radeon HD 4850 X2 512MB		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: Bandwidth is the max amount of data (measured in megabytes per second) that can be transported over the external memory interface in a second. It's worked out by multiplying the bus width by its memory speed. If the card has DDR type RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour 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 output rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.