Radeon HD 4850 X2 1GB vs Radeon HD 7850

Intro

Compare that to the Radeon HD 7850, which has core speeds of 860 MHz on the GPU, and 1200 MHz on the 2048 MB of GDDR5 RAM. It features 1024 SPUs along with 64 Texture Address Units and 32 Rasterization Operator 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 1GB		250 Watts
	Difference: 120 Watts (92%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7850 should be much faster than the Radeon HD 4850 X2 1GB overall. (explain)

Radeon HD 7850		153600 MB/sec
Radeon HD 4850 X2 1GB		127104 MB/sec
	Difference: 26496 (21%)

Texel Rate

The Radeon HD 7850 will be a small bit (more or less 10%) faster with regards to texture filtering than the Radeon HD 4850 X2 1GB. (explain)

Radeon HD 7850		55040 Mtexels/sec
Radeon HD 4850 X2 1GB		50000 Mtexels/sec
	Difference: 5040 (10%)

Pixel Rate

The Radeon HD 7850 should be much (about 38%) faster with regards to full screen anti-aliasing than the Radeon HD 4850 X2 1GB, and also capable of handling higher resolutions without slowing down too much. (explain)

Radeon HD 7850		27520 Mpixels/sec
Radeon HD 4850 X2 1GB		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 (counted in megabytes per second) that can be transported over the external memory interface in one second. It's worked out by multiplying the interface width by the speed of its memory. If it uses DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better 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 processed 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 higher this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly record to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.