Radeon HD 3850 X2 vs Radeon HD 4870 2GB

Intro

Compare all that to the Radeon HD 4870 2GB, which comes with a core clock frequency of 750 MHz and a GDDR5 memory speed of 900 MHz. It also uses a 256-bit memory bus, and makes use of a 55 nm design. It is made up of 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically, the Radeon HD 4870 2GB should be a bit faster than the Radeon HD 3850 X2 in general. (explain)

Radeon HD 4870 2GB		115200 MB/sec
Radeon HD 3850 X2		105984 MB/sec
	Difference: 9216 (9%)

Texel Rate

The Radeon HD 4870 2GB is quite a bit (approximately 40%) better at AF than the Radeon HD 3850 X2. (explain)

Radeon HD 4870 2GB		30000 Mtexels/sec
Radeon HD 3850 X2		21376 Mtexels/sec
	Difference: 8624 (40%)

Pixel Rate

The Radeon HD 3850 X2 will be much (more or less 78%) better at AA than the Radeon HD 4870 2GB, and also should be capable of handling higher resolutions without losing too much performance. (explain)

Radeon HD 3850 X2		21376 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 9376 (78%)

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 max amount of data (counted in MB per second) that can be transferred across the external memory interface in one second. The number is calculated by multiplying the interface width by its memory clock speed. In the case of DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster the card will be in general. It especially helps with AA, 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 is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The better this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.