Radeon HD 4830 1GB vs Radeon HD 7990

Intro

Compare all of that to the Radeon HD 7990, which features a GPU core clock speed of 950 MHz, and 3072 MB of GDDR5 RAM set to run at 1500 MHz through a 384-bit bus. It also features 2048 SPUs, 128 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4830 1GB		95 Watts
Radeon HD 7990		375 Watts
	Difference: 280 Watts (295%)

Memory Bandwidth

The Radeon HD 7990, in theory, should perform quite a bit faster than the Radeon HD 4830 1GB overall. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 4830 1GB		57600 MB/sec
	Difference: 518400 (900%)

Texel Rate

The Radeon HD 7990 is quite a bit (more or less 1222%) faster with regards to AF than the Radeon HD 4830 1GB. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 4830 1GB		18400 Mtexels/sec
	Difference: 224800 (1222%)

Pixel Rate

The Radeon HD 7990 will be a lot (more or less 561%) better at full screen anti-aliasing than the Radeon HD 4830 1GB, and also will be capable of handling higher screen resolutions without slowing down too much. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 4830 1GB		9200 Mpixels/sec
	Difference: 51600 (561%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the max amount of data (in units of megabytes per second) that can be transferred across the external memory interface in one second. It is calculated by multiplying the card's interface width by its memory clock speed. If it uses DDR memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Raster Operations Pipelines by the the core 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 is also dependant on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.