Radeon HD 4850 X2 512MB vs Radeon HD 4890 2GB

Intro

Compare all of that to the Radeon HD 4890 2GB, which makes use of a 55 nm design. AMD has set the core frequency at 1000 MHz. The GDDR5 RAM is set to run at a frequency of 975 MHz on this model. It features 800(160x5) SPUs along with 40 TAUs and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4890 2GB		190 Watts
Radeon HD 4850 X2 512MB		250 Watts
	Difference: 60 Watts (32%)

Memory Bandwidth

Theoretically, the Radeon HD 4850 X2 512MB should be a small bit faster than the Radeon HD 4890 2GB in general. (explain)

Radeon HD 4850 X2 512MB		127104 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 2304 (2%)

Texel Rate

The Radeon HD 4850 X2 512MB should be a lot (about 25%) faster with regards to AF than the Radeon HD 4890 2GB. (explain)

Radeon HD 4850 X2 512MB		50000 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 10000 (25%)

Pixel Rate

The Radeon HD 4850 X2 512MB should be a lot (approximately 25%) faster with regards to FSAA than the Radeon HD 4890 2GB, and will be able to handle higher screen resolutions while still performing well. (explain)

Radeon HD 4850 X2 512MB		20000 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 4000 (25%)

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 MB per second) that can be transferred across the external memory interface in a second. It is calculated by multiplying the bus width by its memory speed. If it uses DDR memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed per second. This number is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The higher the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the most pixels the video card can possibly write to the local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.