Radeon HD 4870 X2 vs Radeon HD 6790

Intro

Compare all that to the Radeon HD 6790, which has GPU core speed of 840 MHz, and 1024 MB of GDDR5 RAM set to run at 1050 MHz through a 256-bit bus. It also is comprised of 800 SPUs, 40 TAUs, and 16 Raster Operation Units.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6790		150 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 200 Watts (133%)

Memory Bandwidth

As far as performance goes, the Radeon HD 4870 X2 should in theory be much superior to the Radeon HD 6790 overall. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 6790		134400 MB/sec
	Difference: 96000 (71%)

Texel Rate

The Radeon HD 4870 X2 should be quite a bit (more or less 79%) better at texture filtering than the Radeon HD 6790. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 6790		33600 Mtexels/sec
	Difference: 26400 (79%)

Pixel Rate

The Radeon HD 4870 X2 is much (about 79%) faster with regards to AA than the Radeon HD 6790, and also will be capable of handling higher screen resolutions better. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 6790		13440 Mpixels/sec
	Difference: 10560 (79%)

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 maximum amount of information (in units of MB per second) that can be moved past the external memory interface in one second. The number is calculated by multiplying the card's interface width by its memory clock speed. If it uses DDR RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed per second. This number is calculated 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 texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one 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. Pixel rate is calculated by multiplying the number of ROPs by the the card's 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 many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.