Radeon HD 3870 X2 512MB vs Radeon HD 4850 512MB

Intro

Compare those specifications to the Radeon HD 4850 512MB, which features core clock speeds of 625 MHz on the GPU, and 993 MHz on the 512 MB of GDDR3 RAM. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 3870 X2 512MB should in theory be much better than the Radeon HD 4850 512MB in general. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 51648 (81%)

Texel Rate

The Radeon HD 3870 X2 512MB will be a bit (about 6%) more effective at AF than the Radeon HD 4850 512MB. (explain)

Radeon HD 3870 X2 512MB		26400 Mtexels/sec
Radeon HD 4850 512MB		25000 Mtexels/sec
	Difference: 1400 (6%)

Pixel Rate

The Radeon HD 3870 X2 512MB will be quite a bit (approximately 164%) more effective at FSAA than the Radeon HD 4850 512MB, and also capable of handling higher screen resolutions better. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 16400 (164%)

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 information (counted in MB per second) that can be transferred across the external memory interface in a second. It's calculated by multiplying the card's interface width by its memory clock speed. If it uses 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 AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This is calculated by multiplying the total amount of texture units by the core speed of the chip. The better this number, the better the 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 maximum number of pixels that the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units 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 rate also depends on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.