Radeon HD 4870 512MB vs Radeon HD 6750 1GB

Intro

Compare that to the Radeon HD 6750 1GB, which has GPU clock speed of 725 MHz, and 1024 MB of GDDR5 RAM running at 1000 MHz through a 128-bit bus. It also is comprised of 720 Stream Processors, 36 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6750 1GB		86 Watts
Radeon HD 4870 512MB		150 Watts
	Difference: 64 Watts (74%)

Memory Bandwidth

Theoretically, the Radeon HD 4870 512MB should perform much faster than the Radeon HD 6750 1GB in general. (explain)

Radeon HD 4870 512MB		115200 MB/sec
Radeon HD 6750 1GB		64000 MB/sec
	Difference: 51200 (80%)

Texel Rate

The Radeon HD 4870 512MB is a bit (approximately 15%) more effective at AF than the Radeon HD 6750 1GB. (explain)

Radeon HD 4870 512MB		30000 Mtexels/sec
Radeon HD 6750 1GB		26100 Mtexels/sec
	Difference: 3900 (15%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 4870 512MB is superior to the Radeon HD 6750 1GB, but not by far. (explain)

Radeon HD 4870 512MB		12000 Mpixels/sec
Radeon HD 6750 1GB		11600 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 (counted in megabytes per second) that can be transferred over the external memory interface in a second. It's worked out by multiplying the card's bus width by its memory clock speed. If it uses DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the better 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 figure is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The better this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out 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 drawing the pixels (image) on the screen. The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.