Radeon HD 4870 X2 vs Radeon HD 7750

Intro

Compare those specs to the Radeon HD 7750, which has a clock speed of 800 MHz and a GDDR5 memory speed of 1125 MHz. It also makes use of a 128-bit bus, and uses a 28 nm design. It is comprised of 512 SPUs, 32 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7750		55 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 295 Watts (536%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 X2 should perform much faster than the Radeon HD 7750 in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 7750		72000 MB/sec
	Difference: 158400 (220%)

Texel Rate

The Radeon HD 4870 X2 should be a lot (more or less 134%) faster with regards to texture filtering than the Radeon HD 7750. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 7750		25600 Mtexels/sec
	Difference: 34400 (134%)

Pixel Rate

The Radeon HD 4870 X2 will be quite a bit (more or less 88%) faster with regards to full screen anti-aliasing than the Radeon HD 7750, and also should be able to handle higher resolutions while still performing well. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 7750		12800 Mpixels/sec
	Difference: 11200 (88%)

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 max amount of data (in units of MB per second) that can be transported across the external memory interface in one second. It is worked out by multiplying the card's interface width by the speed of its memory. In the case of DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied per second. This is worked out 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 processed in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly record to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.