Radeon HD 4850 512MB vs Radeon HD 6790

Intro

Compare all of that to the Radeon HD 6790, which has a GPU core clock speed of 840 MHz, and 1024 MB of GDDR5 RAM set to run at 1050 MHz through a 256-bit bus. It also features 800 SPUs, 40 Texture Address Units, and 16 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 6790		150 Watts
	Difference: 40 Watts (36%)

Memory Bandwidth

Theoretically, the Radeon HD 6790 should perform a lot faster than the Radeon HD 4850 512MB overall. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 70848 (111%)

Texel Rate

The Radeon HD 6790 is much (approximately 34%) more effective at anisotropic filtering than the Radeon HD 4850 512MB. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 4850 512MB		25000 Mtexels/sec
	Difference: 8600 (34%)

Pixel Rate

The Radeon HD 6790 is quite a bit (about 34%) more effective at anti-aliasing than the Radeon HD 4850 512MB, and should be capable of handling higher screen resolutions while still performing well. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 3440 (34%)

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 information (counted in MB per second) that can be transferred over the external memory interface within a second. The number is worked out by multiplying the interface width by its memory speed. If the card has DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly record to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of ROPs 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 also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.