Radeon HD 3850 256MB vs Radeon HD 7990

Intro

Compare those specifications to the Radeon HD 7990, which has GPU clock speed of 950 MHz, and 3072 MB of GDDR5 memory set to run at 1500 MHz through a 384-bit bus. It also features 2048 Stream Processors, 128 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3850 256MB		75 Watts
Radeon HD 7990		375 Watts
	Difference: 300 Watts (400%)

Memory Bandwidth

The Radeon HD 7990 should in theory be a lot faster than the Radeon HD 3850 256MB overall. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 3850 256MB		52992 MB/sec
	Difference: 523008 (987%)

Texel Rate

The Radeon HD 7990 should be quite a bit (about 2175%) more effective at texture filtering than the Radeon HD 3850 256MB. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 3850 256MB		10688 Mtexels/sec
	Difference: 232512 (2175%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 7990 is the winner, and very much so. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 3850 256MB		10688 Mpixels/sec
	Difference: 50112 (469%)

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 (counted in megabytes per second) that can be transported across the external memory interface within a second. It is calculated by multiplying the bus width by its memory clock speed. If the card has DDR RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, 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 texture map elements (texels) that can be processed in one second. This is calculated by multiplying the total texture units of the card by the core speed of the chip. The higher the texel rate, the better the video 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 amount of pixels that the graphics card could possibly write to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.