Radeon HD 4870 X2 vs Radeon HD 7790

Intro

Compare that to the Radeon HD 7790, which features a clock frequency of 1000 MHz and a GDDR5 memory frequency of 1500 MHz. It also makes use of a 128-bit memory bus, and makes use of a 28 nm design. It is comprised of 896 SPUs, 56 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7790		85 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 265 Watts (312%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 X2 should perform quite a bit faster than the Radeon HD 7790 overall. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 7790		96000 MB/sec
	Difference: 134400 (140%)

Texel Rate

The Radeon HD 4870 X2 should be a little bit (about 7%) faster with regards to texture filtering than the Radeon HD 7790. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 7790		56000 Mtexels/sec
	Difference: 4000 (7%)

Pixel Rate

The Radeon HD 4870 X2 will be much (approximately 50%) better at full screen anti-aliasing than the Radeon HD 7790, and capable of handling higher resolutions without slowing down too much. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 7790		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: Memory bandwidth is the largest amount of information (in units of MB per second) that can be transported across the external memory interface in a second. It's worked out by multiplying the card's bus width by its memory speed. If it uses DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.