Radeon HD 6770 1GB vs Radeon HD 7990

Intro

Compare those specifications to the Radeon HD 7990, which features clock speeds of 950 MHz on the GPU, and 1500 MHz on the 3072 MB of GDDR5 RAM. It features 2048 SPUs as well as 128 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6770 1GB		108 Watts
Radeon HD 7990		375 Watts
	Difference: 267 Watts (247%)

Memory Bandwidth

In theory, the Radeon HD 7990 should perform much faster than the Radeon HD 6770 1GB overall. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 6770 1GB		67200 MB/sec
	Difference: 508800 (757%)

Texel Rate

The Radeon HD 7990 will be a lot (more or less 576%) faster with regards to texture filtering than the Radeon HD 6770 1GB. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 6770 1GB		36000 Mtexels/sec
	Difference: 207200 (576%)

Pixel Rate

The Radeon HD 7990 will be much (about 322%) better at FSAA than the Radeon HD 6770 1GB, and able to handle higher resolutions more effectively. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 6770 1GB		14400 Mpixels/sec
	Difference: 46400 (322%)

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 largest amount of information (in units of MB per second) that can be moved past the external memory interface within a second. It's worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR type memory, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster 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 can be applied in one second. This figure is worked out by multiplying the total texture units by the core clock speed of the chip. The better this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes 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, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.