Radeon HD 4850 X2 512MB vs Radeon HD 7850

Intro

Compare those specs to the Radeon HD 7850, which features a GPU core clock speed of 860 MHz, and 2048 MB of GDDR5 RAM running at 1200 MHz through a 256-bit bus. It also features 1024 SPUs, 64 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7850		130 Watts
Radeon HD 4850 X2 512MB		250 Watts
	Difference: 120 Watts (92%)

Memory Bandwidth

Performance-wise, the Radeon HD 7850 should in theory be much superior to the Radeon HD 4850 X2 512MB overall. (explain)

Radeon HD 7850		153600 MB/sec
Radeon HD 4850 X2 512MB		127104 MB/sec
	Difference: 26496 (21%)

Texel Rate

The Radeon HD 7850 is a little bit (about 10%) more effective at anisotropic filtering than the Radeon HD 4850 X2 512MB. (explain)

Radeon HD 7850		55040 Mtexels/sec
Radeon HD 4850 X2 512MB		50000 Mtexels/sec
	Difference: 5040 (10%)

Pixel Rate

The Radeon HD 7850 should be much (approximately 38%) better at FSAA than the Radeon HD 4850 X2 512MB, and able to handle higher screen resolutions without slowing down too much. (explain)

Radeon HD 7850		27520 Mpixels/sec
Radeon HD 4850 X2 512MB		20000 Mpixels/sec
	Difference: 7520 (38%)

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 data (in units of megabytes per second) that can be transferred past the external memory interface within a second. It's worked out by multiplying the card's bus width by its memory speed. If the card has DDR memory, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly write to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.