Radeon HD 4890 1GB vs Radeon HD 7850

Intro

Compare those specifications to the Radeon HD 7850, which features core speeds of 860 MHz on the GPU, and 1200 MHz on the 2048 MB of GDDR5 memory. It features 1024 SPUs as well as 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 1GB		190 Watts
	Difference: 60 Watts (46%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7850 will be 23% quicker than the Radeon HD 4890 1GB overall, because of its higher bandwidth. (explain)

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

Texel Rate

The Radeon HD 7850 will 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 (approximately 72%) more effective at anti-aliasing than the Radeon HD 4890 1GB, and will be capable of handling higher resolutions without losing too much performance. (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: Memory bandwidth is the maximum amount of information (in units of megabytes per second) that can be transferred across the external memory interface in a second. It is worked out by multiplying the card's bus width by its memory clock speed. In the case of DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. 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 texture map elements (texels) that are applied per second. This number is worked out by multiplying the total number of texture units by the core speed of the chip. The higher the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour 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 rate is also dependant on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.