Radeon HD 4890 2GB vs Radeon HD 7790

Intro

Compare that to the Radeon HD 7790, which features a core clock speed of 1000 MHz and a GDDR5 memory speed of 1500 MHz. It also features a 128-bit memory bus, and uses a 28 nm design. It is comprised of 896 SPUs, 56 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7790		85 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 105 Watts (124%)

Memory Bandwidth

In theory, the Radeon HD 4890 2GB will be 30% quicker than the Radeon HD 7790 in general, because of its greater data rate. (explain)

Radeon HD 4890 2GB		124800 MB/sec
Radeon HD 7790		96000 MB/sec
	Difference: 28800 (30%)

Texel Rate

The Radeon HD 7790 is quite a bit (about 40%) faster with regards to anisotropic filtering than the Radeon HD 4890 2GB. (explain)

Radeon HD 7790		56000 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 16000 (40%)

Pixel Rate

Both cards have exactly the same pixel fill rate, so theoretically they should perform equally good at at FSAA, and be able to handle the same resolutions. (explain)

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.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the largest amount of data (counted in MB per second) that can be transported past the external memory interface in one second. The number is worked out by multiplying the card's interface width by the speed of its memory. If it uses DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better 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 can be applied per second. This is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The higher this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to the local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.