Radeon HD 4850 512MB vs Radeon HD 7850

Intro

Compare all that to the Radeon HD 7850, which has GPU clock speed of 860 MHz, and 2048 MB of GDDR5 RAM set to run at 1200 MHz through a 256-bit bus. It also features 1024 Stream Processors, 64 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 512MB		110 Watts
Radeon HD 7850		130 Watts
	Difference: 20 Watts (18%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7850 should be 142% faster than the Radeon HD 4850 512MB in general, because of its greater data rate. (explain)

Radeon HD 7850		153600 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 90048 (142%)

Texel Rate

The Radeon HD 7850 should be a lot (more or less 120%) more effective at AF than the Radeon HD 4850 512MB. (explain)

Radeon HD 7850		55040 Mtexels/sec
Radeon HD 4850 512MB		25000 Mtexels/sec
	Difference: 30040 (120%)

Pixel Rate

The Radeon HD 7850 will be quite a bit (about 175%) better at AA than the Radeon HD 4850 512MB, and also will be capable of handling higher screen resolutions while still performing well. (explain)

Radeon HD 7850		27520 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 17520 (175%)

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.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the largest amount of data (counted in MB per second) that can be transported across the external memory interface within a second. It's worked out by multiplying the bus width by the speed of its memory. If the card has DDR type memory, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly record to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.