Radeon HD 4850 1GB vs Radeon HD 7990

Intro

Compare that to the Radeon HD 7990, which features a clock speed of 950 MHz and a GDDR5 memory frequency of 1500 MHz. It also features a 384-bit bus, and uses a 28 nm design. It is made up of 2048 SPUs, 128 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 1GB		110 Watts
Radeon HD 7990		375 Watts
	Difference: 265 Watts (241%)

Memory Bandwidth

The Radeon HD 7990, in theory, should perform a lot faster than the Radeon HD 4850 1GB in general. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 4850 1GB		63552 MB/sec
	Difference: 512448 (806%)

Texel Rate

The Radeon HD 7990 should be a lot (more or less 873%) better at anisotropic filtering than the Radeon HD 4850 1GB. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 4850 1GB		25000 Mtexels/sec
	Difference: 218200 (873%)

Pixel Rate

The Radeon HD 7990 will be much (more or less 508%) better at AA than the Radeon HD 4850 1GB, and able to handle higher screen resolutions without slowing down too much. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 4850 1GB		10000 Mpixels/sec
	Difference: 50800 (508%)

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: Bandwidth is the max amount of information (counted in MB per second) that can be moved past the external memory interface within a second. It's worked out by multiplying the card's bus width by its memory speed. In the case of DDR type RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, 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 number of texture map elements (texels) that can be applied in one second. This is worked out 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 a second - measured in millions of pixels per second. The number is worked out by multiplying the number of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.