Radeon HD 4890 2GB vs Radeon HD 7850

Intro

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

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

Performance-wise, the Radeon HD 7850 should theoretically be quite a bit better 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 should be quite a bit (approximately 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

If running with high levels of AA is important to you, then the Radeon HD 7850 is the winner, and very much so. (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 information (in units of megabytes per second) that can be transported across the external memory interface in a second. It is worked out by multiplying the interface width by its memory clock speed. If it uses DDR memory, it must be multiplied by 2 once again. If it uses 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, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one second. This number is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

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