Radeon HD 7990 vs Radeon RX 6800 XT

Intro

Compare all that to the Radeon RX 6800 XT, which has a clock speed of 1825 MHz and a GDDR6 memory frequency of 2000 MHz. It also makes use of a 256-bit memory bus, and makes use of a 7 nm design. It features 4608 SPUs, 288 TAUs, and 128 Raster Operation 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

Theoretically, the Radeon HD 7990 should be a 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 is quite a bit (approximately 116%) better at 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 is a lot (about 284%) better at anti-aliasing than the Radeon HD 7990, and also able to handle higher screen resolutions without slowing down too much. (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 max amount of data (measured in megabytes per second) that can be transferred across the external memory interface within a second. It's calculated by multiplying the bus width by the speed of its memory. If it uses DDR type memory, the result should be multiplied by 2 once 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 anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed in one second. This number is worked out by multiplying the total number of texture units by the core clock speed of the chip. The better 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 amount of pixels that the graphics chip could possibly record to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.