Radeon HD 4870 2GB vs Radeon HD 5850

Intro

Compare those specifications to the Radeon HD 5850, which features a GPU core clock speed of 725 MHz, and 1024 MB of GDDR5 RAM running at 1000 MHz through a 256-bit bus. It also is comprised of 1440(288x5) Stream Processors, 72 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 2GB		150 Watts
Radeon HD 5850		151 Watts
	Difference: 1 Watts (1%)

Memory Bandwidth

In theory, the Radeon HD 5850 is 11% quicker than the Radeon HD 4870 2GB overall, because of its higher data rate. (explain)

Radeon HD 5850		128000 MB/sec
Radeon HD 4870 2GB		115200 MB/sec
	Difference: 12800 (11%)

Texel Rate

The Radeon HD 5850 will be quite a bit (approximately 74%) more effective at texture filtering than the Radeon HD 4870 2GB. (explain)

Radeon HD 5850		52200 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 22200 (74%)

Pixel Rate

The Radeon HD 5850 should be much (about 93%) more effective at anti-aliasing than the Radeon HD 4870 2GB, and capable of handling higher screen resolutions while still performing well. (explain)

Radeon HD 5850		23200 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 11200 (93%)

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 MB per second) that can be transferred across the external memory interface within a second. It's worked out by multiplying the bus width by its memory clock speed. In the case of DDR type RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card can possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.