Radeon HD 7990 vs Radeon RX 6600 XT

Intro

Compare those specs to the Radeon RX 6600 XT, which uses a 7 nm design. AMD has set the core speed at 1968 MHz. The GDDR6 RAM is set to run at a speed of 2000 MHz on this specific card. It features 2048 SPUs as well as 128 TAUs and 64 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon RX 6600 XT		160 Watts
Radeon HD 7990		375 Watts
	Difference: 215 Watts (134%)

Memory Bandwidth

In theory, the Radeon HD 7990 is 120% faster than the Radeon RX 6600 XT overall, because of its greater data rate. (explain)

Radeon HD 7990		576000 MB/sec
Radeon RX 6600 XT		262144 MB/sec
	Difference: 313856 (120%)

Texel Rate

The Radeon RX 6600 XT should be just a bit (more or less 4%) faster with regards to texture filtering than the Radeon HD 7990. (explain)

Radeon RX 6600 XT		251904 Mtexels/sec
Radeon HD 7990		243200 Mtexels/sec
	Difference: 8704 (4%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon RX 6600 XT is a better choice, by a large margin. (explain)

Radeon RX 6600 XT		125952 Mpixels/sec
Radeon HD 7990		60800 Mpixels/sec
	Difference: 65152 (107%)

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 largest amount of data (counted in MB per second) that can be transferred past the external memory interface within a second. It is worked out by multiplying the card's interface width by its memory speed. If it uses DDR RAM, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, 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 can be processed in one second. This number is worked out by multiplying the total texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one 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 worked out by multiplying the number of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.