Radeon HD 4870 X2 vs Radeon HD 5870

Intro

Compare those specs to the Radeon HD 5870, which features GPU clock speed of 850 MHz, and 1024 MB of GDDR5 RAM running at 1200 MHz through a 256-bit bus. It also is made up of 1600(320x5) SPUs, 80 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 5870		188 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 162 Watts (86%)

Memory Bandwidth

Theoretically, the Radeon HD 4870 X2 should perform much faster than the Radeon HD 5870 in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 5870		153600 MB/sec
	Difference: 76800 (50%)

Texel Rate

The Radeon HD 5870 will be a bit (approximately 13%) better at texture filtering than the Radeon HD 4870 X2. (explain)

Radeon HD 5870		68000 Mtexels/sec
Radeon HD 4870 X2		60000 Mtexels/sec
	Difference: 8000 (13%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 5870 is a better choice, but only just. (explain)

Radeon HD 5870		27200 Mpixels/sec
Radeon HD 4870 X2		24000 Mpixels/sec
	Difference: 3200 (13%)

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 megabytes per second) that can be moved past the external memory interface in a second. It's calculated by multiplying the card's interface width by its memory speed. If the card has 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 amount of texture map elements (texels) that can be processed per second. This is calculated by multiplying the total texture units by the core clock speed of the chip. The better this number, the better the graphics card will be at handling 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 record to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.