Radeon HD 4870 X2 vs Radeon HD 7770

Intro

Compare that to the Radeon HD 7770, which uses a 28 nm design. AMD has set the core frequency at 1000 MHz. The GDDR5 memory is set to run at a frequency of 1125 MHz on this specific card. It features 640 SPUs as well as 40 TAUs and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7770		80 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 270 Watts (338%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 X2 should perform quite a bit faster than the Radeon HD 7770 overall. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 7770		72000 MB/sec
	Difference: 158400 (220%)

Texel Rate

The Radeon HD 4870 X2 should be a lot (approximately 50%) more effective at texture filtering than the Radeon HD 7770. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 7770		40000 Mtexels/sec
	Difference: 20000 (50%)

Pixel Rate

The Radeon HD 4870 X2 is quite a bit (more or less 50%) faster with regards to FSAA than the Radeon HD 7770, and also able to handle higher resolutions without slowing down too much. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 7770		16000 Mpixels/sec
	Difference: 8000 (50%)

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 (counted in MB per second) that can be transported across the external memory interface in one second. It is worked out by multiplying the bus width by its memory speed. In the case of DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This number is worked out by multiplying the total 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 a second.

Pixel Rate: Pixel rate is the most pixels the video card can possibly record to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill 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.