Radeon HD 3870 1GB vs Radeon HD 4850 1GB

Intro

Compare that to the Radeon HD 4850 1GB, which features a core clock frequency of 625 MHz and a GDDR4 memory speed of 993 MHz. It also makes use of a 256-bit bus, and uses a 55 nm design. It is made up of 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3870 1GB		106 Watts
Radeon HD 4850 1GB		110 Watts
	Difference: 4 Watts (4%)

Memory Bandwidth

Theoretically, the Radeon HD 3870 1GB should perform a small bit faster than the Radeon HD 4850 1GB overall. (explain)

Radeon HD 3870 1GB		72000 MB/sec
Radeon HD 4850 1GB		63552 MB/sec
	Difference: 8448 (13%)

Texel Rate

The Radeon HD 4850 1GB will be a lot (about 102%) better at anisotropic filtering than the Radeon HD 3870 1GB. (explain)

Radeon HD 4850 1GB		25000 Mtexels/sec
Radeon HD 3870 1GB		12400 Mtexels/sec
	Difference: 12600 (102%)

Pixel Rate

The Radeon HD 3870 1GB should be a lot (more or less 24%) faster with regards to full screen anti-aliasing than the Radeon HD 4850 1GB, and also should be capable of handling higher screen resolutions without slowing down too much. (explain)

Radeon HD 3870 1GB		12400 Mpixels/sec
Radeon HD 4850 1GB		10000 Mpixels/sec
	Difference: 2400 (24%)

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 information (measured in MB per second) that can be transported past the external memory interface in one second. The number is worked out by multiplying the bus width by its memory speed. If the card has DDR memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed 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 higher this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly write to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.