Radeon HD 4870 512MB vs Radeon HD 5850

Intro

Compare those specifications to the Radeon HD 5850, which comes with a core clock speed of 725 MHz and a GDDR5 memory speed of 1000 MHz. It also features a 256-bit bus, and uses a 40 nm design. It is made up of 1440(288x5) SPUs, 72 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 512MB		150 Watts
Radeon HD 5850		151 Watts
	Difference: 1 Watts (1%)

Memory Bandwidth

The Radeon HD 5850 should in theory perform just a bit faster than the Radeon HD 4870 512MB in general. (explain)

Radeon HD 5850		128000 MB/sec
Radeon HD 4870 512MB		115200 MB/sec
	Difference: 12800 (11%)

Texel Rate

The Radeon HD 5850 is quite a bit (approximately 74%) faster with regards to AF than the Radeon HD 4870 512MB. (explain)

Radeon HD 5850		52200 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 22200 (74%)

Pixel Rate

The Radeon HD 5850 will be quite a bit (about 93%) more effective at anti-aliasing than the Radeon HD 4870 512MB, and should be capable of handling higher resolutions better. (explain)

Radeon HD 5850		23200 Mpixels/sec
Radeon HD 4870 512MB		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: Bandwidth is the max amount of data (counted in megabytes per second) that can be transported past the external memory interface within a second. The number is worked out by multiplying the interface width by its memory clock speed. If the card has DDR type RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the 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 figure is worked out by multiplying the total texture units of the card by the core speed of the chip. The better this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly write to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the amount 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 filling the screen with pixels (the image). The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.