Radeon HD 4890 1GB vs Radeon HD 7990

Intro

Compare those specs to the Radeon HD 7990, which comes with GPU core speed of 950 MHz, and 3072 MB of GDDR5 RAM set to run at 1500 MHz through a 384-bit bus. It also is made up of 2048 Stream Processors, 128 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4890 1GB		190 Watts
Radeon HD 7990		375 Watts
	Difference: 185 Watts (97%)

Memory Bandwidth

The Radeon HD 7990 should theoretically perform a lot faster than the Radeon HD 4890 1GB in general. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 451200 (362%)

Texel Rate

The Radeon HD 7990 should be a lot (more or less 508%) more effective at anisotropic filtering than the Radeon HD 4890 1GB. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 203200 (508%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 7990 is the winner, by a large margin. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 4890 1GB		16000 Mpixels/sec
	Difference: 44800 (280%)

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 data (in units of MB per second) that can be transported across the external memory interface in one second. The number is worked out by multiplying the bus width by its memory clock speed. In the case of DDR memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly write to its local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.