Radeon HD 4890 2GB vs Radeon HD 7850

Intro

Compare those specifications to the Radeon HD 7850, which uses a 28 nm design. AMD has clocked the core frequency at 860 MHz. The GDDR5 RAM works at a frequency of 1200 MHz on this card. It features 1024 SPUs along with 64 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7850		130 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 60 Watts (46%)

Memory Bandwidth

In theory, the Radeon HD 7850 should be a lot faster than the Radeon HD 4890 2GB in general. (explain)

Radeon HD 7850		153600 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 28800 (23%)

Texel Rate

The Radeon HD 7850 is quite a bit (about 38%) more effective at anisotropic filtering than the Radeon HD 4890 2GB. (explain)

Radeon HD 7850		55040 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 15040 (38%)

Pixel Rate

The Radeon HD 7850 will be quite a bit (approximately 72%) more effective at anti-aliasing than the Radeon HD 4890 2GB, and able to handle higher screen resolutions better. (explain)

Radeon HD 7850		27520 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 11520 (72%)

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.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the maximum amount of data (in units of megabytes per second) that can be transported over the external memory interface within a second. It's worked out by multiplying the card's interface width by its memory speed. If it uses DDR type RAM, 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 anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly write to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.