Radeon HD 3870 512MB vs Radeon HD 4750

Intro

Compare those specifications to the Radeon HD 4750, which comes with a core clock frequency of 730 MHz and a GDDR5 memory speed of 800 MHz. It also features a 128-bit memory bus, and makes use of a 40 nm design. It is comprised of 640(128x5) SPUs, 32 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4750		75 Watts
Radeon HD 3870 512MB		106 Watts
	Difference: 31 Watts (41%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 3870 512MB is 13% quicker than the Radeon HD 4750 in general, because of its higher data rate. (explain)

Radeon HD 3870 512MB		57600 MB/sec
Radeon HD 4750		51200 MB/sec
	Difference: 6400 (13%)

Texel Rate

The Radeon HD 4750 is much (approximately 88%) faster with regards to texture filtering than the Radeon HD 3870 512MB. (explain)

Radeon HD 4750		23360 Mtexels/sec
Radeon HD 3870 512MB		12400 Mtexels/sec
	Difference: 10960 (88%)

Pixel Rate

The Radeon HD 3870 512MB should be a bit (more or less 6%) more effective at anti-aliasing than the Radeon HD 4750, and should be able to handle higher screen resolutions better. (explain)

Radeon HD 3870 512MB		12400 Mpixels/sec
Radeon HD 4750		11680 Mpixels/sec
	Difference: 720 (6%)

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 information (counted in MB per second) that can be transferred over the external memory interface within a second. It's worked out by multiplying the card's interface width by its memory speed. If the card has DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better 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 are applied in one second. This number is worked out by multiplying the total texture units by the core clock speed of the chip. The higher this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to the local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of Raster Operations Pipelines 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 output rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.