Radeon HD 3870 512MB vs Radeon HD 4870 512MB

Intro

Compare those specifications to the Radeon HD 4870 512MB, which comes with GPU clock speed of 750 MHz, and 512 MB of GDDR5 RAM set to run at 900 MHz through a 256-bit bus. It also features 800(160x5) Stream Processors, 40 Texture Address Units, and 16 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3870 512MB		106 Watts
Radeon HD 4870 512MB		150 Watts
	Difference: 44 Watts (42%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 512MB will be 100% quicker than the Radeon HD 3870 512MB overall, because of its higher data rate. (explain)

Radeon HD 4870 512MB		115200 MB/sec
Radeon HD 3870 512MB		57600 MB/sec
	Difference: 57600 (100%)

Texel Rate

The Radeon HD 4870 512MB will be much (approximately 142%) more effective at texture filtering than the Radeon HD 3870 512MB. (explain)

Radeon HD 4870 512MB		30000 Mtexels/sec
Radeon HD 3870 512MB		12400 Mtexels/sec
	Difference: 17600 (142%)

Pixel Rate

The Radeon HD 3870 512MB is a little bit (approximately 3%) more effective at AA than the Radeon HD 4870 512MB, and also will be able to handle higher resolutions more effectively. (explain)

Radeon HD 3870 512MB		12400 Mpixels/sec
Radeon HD 4870 512MB		12000 Mpixels/sec
	Difference: 400 (3%)

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 data (in units of MB per second) that can be transferred over the external memory interface in one second. It's worked out by multiplying the bus width by its memory speed. If the card has DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This is calculated 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 per second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly record to the local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on lots of 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.