Radeon HD 4850 2GB vs Radeon HD 7990

Intro

Compare those specs to the Radeon HD 7990, which has clock speeds of 950 MHz on the GPU, and 1500 MHz on the 3072 MB of GDDR5 memory. It features 2048 SPUs along with 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 2GB		110 Watts
Radeon HD 7990		375 Watts
	Difference: 265 Watts (241%)

Memory Bandwidth

The Radeon HD 7990 should in theory perform a lot faster than the Radeon HD 4850 2GB overall. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 4850 2GB		63552 MB/sec
	Difference: 512448 (806%)

Texel Rate

The Radeon HD 7990 should be quite a bit (more or less 873%) faster with regards to texture filtering than the Radeon HD 4850 2GB. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 4850 2GB		25000 Mtexels/sec
	Difference: 218200 (873%)

Pixel Rate

The Radeon HD 7990 is a lot (approximately 508%) more effective at anti-aliasing than the Radeon HD 4850 2GB, and should be able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 4850 2GB		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 (in units of MB per second) that can be transferred over the external memory interface within a second. The number is calculated by multiplying the bus width by its memory speed. In the case of DDR type memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip 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 ROPs by the clock 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 rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.