Radeon HD 4890 1GB vs Radeon HD 7850

Intro

Compare those specs to the Radeon HD 7850, which comes with a GPU core clock speed of 860 MHz, and 2048 MB of GDDR5 RAM set to run at 1200 MHz through a 256-bit bus. It also is comprised of 1024 Stream Processors, 64 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7850		130 Watts
Radeon HD 4890 1GB		190 Watts
	Difference: 60 Watts (46%)

Memory Bandwidth

The Radeon HD 7850, in theory, should perform much faster than the Radeon HD 4890 1GB overall. (explain)

Radeon HD 7850		153600 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 28800 (23%)

Texel Rate

The Radeon HD 7850 should be a lot (more or less 38%) more effective at texture filtering than the Radeon HD 4890 1GB. (explain)

Radeon HD 7850		55040 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 15040 (38%)

Pixel Rate

The Radeon HD 7850 is a lot (about 72%) more effective at anti-aliasing than the Radeon HD 4890 1GB, and also will be capable of handling higher resolutions more effectively. (explain)

Radeon HD 7850		27520 Mpixels/sec
Radeon HD 4890 1GB		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: Bandwidth is the maximum amount of information (in units of MB per second) that can be transferred past the external memory interface in a second. The number is worked out by multiplying the bus width by its memory clock speed. If it uses DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly write to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.