Radeon HD 3870 X2 512MB vs Radeon HD 6750

Intro

Compare all that to the Radeon HD 6750, which has a core clock speed of 725 MHz and a GDDR5 memory frequency of 1000 MHz. It also makes use of a 128-bit bus, and makes use of a 40 nm design. It features 720 SPUs, 36 Texture Address Units, and 16 ROPs.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 3870 X2 512MB should be a lot faster than the Radeon HD 6750 overall. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
Radeon HD 6750		64000 MB/sec
	Difference: 51200 (80%)

Texel Rate

The Radeon HD 3870 X2 512MB will be a small bit (about 1%) faster with regards to texture filtering than the Radeon HD 6750. (explain)

Radeon HD 3870 X2 512MB		26400 Mtexels/sec
Radeon HD 6750		26100 Mtexels/sec
	Difference: 300 (1%)

Pixel Rate

The Radeon HD 3870 X2 512MB will be quite a bit (about 128%) better at anti-aliasing than the Radeon HD 6750, and will be able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon HD 6750		11600 Mpixels/sec
	Difference: 14800 (128%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the largest amount of data (in units of megabytes per second) that can be moved past the external memory interface within a second. The number is worked out by multiplying the card's interface width by the speed of its memory. In the case of DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to the local memory in one 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 - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.