Radeon HD 4890 2GB vs Radeon HD 7850

Intro

Compare all that to the Radeon HD 7850, which features a clock speed of 860 MHz and a GDDR5 memory speed of 1200 MHz. It also makes use of a 256-bit memory bus, and makes use of a 28 nm design. It is made up of 1024 SPUs, 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 2GB		190 Watts
	Difference: 60 Watts (46%)

Memory Bandwidth

The Radeon HD 7850 should theoretically perform much faster than the Radeon HD 4890 2GB overall. (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 a lot (approximately 38%) better at texture 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 should be quite a bit (approximately 72%) faster with regards to full screen anti-aliasing than the Radeon HD 4890 2GB, and also should be 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: Bandwidth is the maximum amount of information (in units of MB per second) that can be moved past the external memory interface in one second. The number is worked out by multiplying the bus width by its memory speed. If it uses DDR type RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This figure is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The better the texel rate, 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 maximum amount of pixels that the graphics chip can possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the clock 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 output rate also depends on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.