Radeon HD 4850 X2 1GB vs Radeon HD 4870 2GB

Intro

Compare those specs to the Radeon HD 4870 2GB, which uses a 55 nm design. AMD has clocked the core frequency at 750 MHz. The GDDR5 RAM is set to run at a frequency of 900 MHz on this particular card. It features 800(160x5) SPUs along with 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 2GB		150 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 100 Watts (67%)

Memory Bandwidth

As far as performance goes, the Radeon HD 4850 X2 1GB should in theory be just a bit better than the Radeon HD 4870 2GB overall. (explain)

Radeon HD 4850 X2 1GB		127104 MB/sec
Radeon HD 4870 2GB		115200 MB/sec
	Difference: 11904 (10%)

Texel Rate

The Radeon HD 4850 X2 1GB will be a lot (about 67%) more effective at texture filtering than the Radeon HD 4870 2GB. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 20000 (67%)

Pixel Rate

The Radeon HD 4850 X2 1GB should be quite a bit (about 67%) faster with regards to FSAA than the Radeon HD 4870 2GB, and also able to handle higher screen resolutions while still performing well. (explain)

Radeon HD 4850 X2 1GB		20000 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 8000 (67%)

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 information (measured in MB per second) that can be transported past the external memory interface within a second. It's calculated by multiplying the card's interface width by the speed of its memory. If it uses DDR type RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, 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 number 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 card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). 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 bandwidth is, the lower the potential to reach the maximum fill rate.