Radeon HD 4850 2GB vs Radeon HD 6790

Intro

Compare all that to the Radeon HD 6790, which makes use of a 40 nm design. AMD has clocked the core speed at 840 MHz. The GDDR5 memory runs at a frequency of 1050 MHz on this model. It features 800 SPUs along with 40 TAUs 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 a lot 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 is much (more or less 34%) more effective at AF 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 should be a lot (approximately 34%) more effective at full screen anti-aliasing than the Radeon HD 4850 2GB, and also able to handle higher resolutions more effectively. (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 largest amount of information (measured in MB per second) that can be moved over the external memory interface in a second. It is worked out by multiplying the bus width by its memory speed. If the card has DDR memory, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card can possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.