Radeon HD 4770 vs Radeon HD 7990

Intro

Compare that to the Radeon HD 7990, which has a clock frequency of 950 MHz and a GDDR5 memory frequency of 1500 MHz. It also uses a 384-bit memory bus, and makes use of a 28 nm design. It is comprised 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

Theoretically speaking, the Radeon HD 7990 should perform quite a bit faster than the Radeon HD 4770 in general. (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 (approximately 913%) faster with regards to texture filtering than the Radeon HD 4770. (explain)

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

Pixel Rate

If running with a high resolution is important to you, then the Radeon HD 7990 is superior to the Radeon HD 4770, by far. (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: Bandwidth is the maximum amount of information (measured in megabytes per second) that can be transported across the external memory interface within a second. It's worked out by multiplying the bus width by its memory speed. In the case of DDR memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied per second. This number is worked out by multiplying the total number of 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 per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly write to its local memory in one 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 speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.