Radeon HD 4830 1GB vs Radeon HD 6790

Intro

Compare those specifications to the Radeon HD 6790, which features GPU clock speed of 840 MHz, and 1024 MB of GDDR5 RAM set to run at 1050 MHz through a 256-bit bus. It also is comprised of 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 4830 1GB		95 Watts
Radeon HD 6790		150 Watts
	Difference: 55 Watts (58%)

Memory Bandwidth

Theoretically, the Radeon HD 6790 should perform a lot faster than the Radeon HD 4830 1GB overall. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4830 1GB		57600 MB/sec
	Difference: 76800 (133%)

Texel Rate

The Radeon HD 6790 will be a lot (about 83%) more effective at texture filtering than the Radeon HD 4830 1GB. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 4830 1GB		18400 Mtexels/sec
	Difference: 15200 (83%)

Pixel Rate

The Radeon HD 6790 is quite a bit (approximately 46%) more effective at anti-aliasing than the Radeon HD 4830 1GB, and also should be able to handle higher resolutions better. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon HD 4830 1GB		9200 Mpixels/sec
	Difference: 4240 (46%)

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 maximum amount of information (counted in megabytes per second) that can be transported past the external memory interface in a second. The number is worked out by multiplying the card's bus width by its memory clock speed. If it uses DDR type RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.