Radeon HD 7990 vs Radeon RX 6800 XT

Intro

Compare those specs to the Radeon RX 6800 XT, which makes use of a 7 nm design. AMD has set the core speed at 1825 MHz. The GDDR6 memory runs at a speed of 2000 MHz on this specific card. It features 4608 SPUs along with 288 TAUs and 128 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon RX 6800 XT		300 Watts
Radeon HD 7990		375 Watts
	Difference: 75 Watts (25%)

Memory Bandwidth

The Radeon HD 7990 should theoretically perform a little bit faster than the Radeon RX 6800 XT overall. (explain)

Radeon HD 7990		576000 MB/sec
Radeon RX 6800 XT		524288 MB/sec
	Difference: 51712 (10%)

Texel Rate

The Radeon RX 6800 XT should be quite a bit (about 116%) faster with regards to AF than the Radeon HD 7990. (explain)

Radeon RX 6800 XT		525600 Mtexels/sec
Radeon HD 7990		243200 Mtexels/sec
	Difference: 282400 (116%)

Pixel Rate

The Radeon RX 6800 XT should be a lot (more or less 284%) better at AA than the Radeon HD 7990, and will be able to handle higher resolutions while still performing well. (explain)

Radeon RX 6800 XT		233600 Mpixels/sec
Radeon HD 7990		60800 Mpixels/sec
	Difference: 172800 (284%)

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 maximum amount of data (measured in megabytes per second) that can be transferred over the external memory interface in one second. It's worked out by multiplying the bus width by its memory speed. If it uses DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the card's 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 are applied in one second. This figure is worked out 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 video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly write to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.