Radeon HD 4870 X2 vs Radeon HD 7990

Intro

Compare all that to the Radeon HD 7990, which features a clock frequency of 950 MHz and a GDDR5 memory speed of 1500 MHz. It also makes use of a 384-bit bus, and uses a 28 nm design. It is comprised of 2048 SPUs, 128 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 X2		350 Watts
Radeon HD 7990		375 Watts
	Difference: 25 Watts (7%)

Memory Bandwidth

In theory, the Radeon HD 7990 should be 150% quicker than the Radeon HD 4870 X2 in general, because of its greater data rate. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 4870 X2		230400 MB/sec
	Difference: 345600 (150%)

Texel Rate

The Radeon HD 7990 is much (more or less 305%) better at anisotropic filtering than the Radeon HD 4870 X2. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 4870 X2		60000 Mtexels/sec
	Difference: 183200 (305%)

Pixel Rate

The Radeon HD 7990 will be a lot (approximately 153%) more effective at FSAA than the Radeon HD 4870 X2, and also will be capable of handling higher screen resolutions more effectively. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 4870 X2		24000 Mpixels/sec
	Difference: 36800 (153%)

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 data (in units of MB per second) that can be moved across the external memory interface in one second. It is calculated by multiplying the card's bus width by its memory speed. In the case of DDR RAM, it should be multiplied by 2 once 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 AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.