Radeon HD 7990 vs Radeon RX 6600 XT

Intro

Compare all that to the Radeon RX 6600 XT, which makes use of a 7 nm design. AMD has set the core speed at 1968 MHz. The GDDR6 memory is set to run at a speed of 2000 MHz on this model. It features 2048 SPUs as well as 128 Texture Address Units 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

Performance-wise, the Radeon HD 7990 should theoretically be much better than the Radeon RX 6600 XT overall. (explain)

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

Texel Rate

The Radeon RX 6600 XT will be a little bit (more or less 4%) more effective at AF 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 using a high resolution is important to you, then the Radeon RX 6600 XT is the winner, by far. (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 megabytes per second) that can be transported over the external memory interface in a second. It's worked out by multiplying the interface width by its memory clock speed. If the card has DDR type RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the better 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 figure is worked out by multiplying the total texture units of the card by the core 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 in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly record to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - aka 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 memory bandwidth is, the lower the ability to reach the maximum fill rate.