Radeon HD 4770 vs Radeon HD 7990

Intro

Compare that to the Radeon HD 7990, which has a core clock speed of 950 MHz and a GDDR5 memory speed of 1500 MHz. It also makes use of a 384-bit memory bus, and uses a 28 nm design. It is made up of 2048 SPUs, 128 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4770		80 Watts
Radeon HD 7990		375 Watts
	Difference: 295 Watts (369%)

Memory Bandwidth

In theory, the Radeon HD 7990 will be 1025% faster than the Radeon HD 4770 in general, due to its greater bandwidth. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 4770		51200 MB/sec
	Difference: 524800 (1025%)

Texel Rate

The Radeon HD 7990 should be a lot (about 913%) faster with regards to anisotropic filtering than the Radeon HD 4770. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 4770		24000 Mtexels/sec
	Difference: 219200 (913%)

Pixel Rate

The Radeon HD 7990 will be a lot (about 407%) faster with regards to full screen anti-aliasing than the Radeon HD 4770, and will be capable of handling higher screen resolutions better. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 4770		12000 Mpixels/sec
	Difference: 48800 (407%)

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 (in units of megabytes per second) that can be moved over the external memory interface in a second. It's calculated by multiplying the card's bus width by its memory clock speed. If the card has DDR memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed per second. This number is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The better the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly write to its local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.