Radeon HD 4850 2GB vs Radeon HD 6790

Intro

Compare those specifications to the Radeon HD 6790, which has GPU core speed of 840 MHz, and 1024 MB of GDDR5 RAM running at 1050 MHz through a 256-bit bus. It also is made up of 800 SPUs, 40 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 2GB		110 Watts
Radeon HD 6790		150 Watts
	Difference: 40 Watts (36%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6790 should be much faster than the Radeon HD 4850 2GB overall. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4850 2GB		63552 MB/sec
	Difference: 70848 (111%)

Texel Rate

The Radeon HD 6790 should be much (about 34%) better at texture filtering than the Radeon HD 4850 2GB. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 4850 2GB		25000 Mtexels/sec
	Difference: 8600 (34%)

Pixel Rate

The Radeon HD 6790 will be a lot (more or less 34%) more effective at AA than the Radeon HD 4850 2GB, and will be able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon HD 4850 2GB		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: Memory bandwidth is the maximum amount of data (counted in MB per second) that can be moved across the external memory interface in one second. It is calculated by multiplying the interface width by the speed of its memory. If it uses DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This number is calculated by multiplying the total texture units of the card by the core clock 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 in a second.

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