Radeon HD 3870 512MB vs Radeon HD 4850 2GB

Intro

Compare those specifications to the Radeon HD 4850 2GB, which makes use of a 55 nm design. ATi has clocked the core speed at 625 MHz. The GDDR4 memory is set to run at a speed of 993 MHz on this particular card. It features 800(160x5) SPUs along with 40 TAUs and 16 ROPs.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3870 512MB		106 Watts
Radeon HD 4850 2GB		110 Watts
	Difference: 4 Watts (4%)

Memory Bandwidth

In theory, the Radeon HD 4850 2GB should be a little bit faster than the Radeon HD 3870 512MB in general. (explain)

Radeon HD 4850 2GB		63552 MB/sec
Radeon HD 3870 512MB		57600 MB/sec
	Difference: 5952 (10%)

Texel Rate

The Radeon HD 4850 2GB is a lot (about 102%) more effective at texture filtering than the Radeon HD 3870 512MB. (explain)

Radeon HD 4850 2GB		25000 Mtexels/sec
Radeon HD 3870 512MB		12400 Mtexels/sec
	Difference: 12600 (102%)

Pixel Rate

The Radeon HD 3870 512MB will be a lot (approximately 24%) faster with regards to AA than the Radeon HD 4850 2GB, and also capable of handling higher resolutions while still performing well. (explain)

Radeon HD 3870 512MB		12400 Mpixels/sec
Radeon HD 4850 2GB		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 data (counted in MB per second) that can be moved over the external memory interface in a second. It is worked out by multiplying the card's bus width by the speed of its memory. If it uses DDR memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed per second. This is worked out by multiplying the total texture units by the core clock speed of the chip. The higher the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of colour ROPs 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 fill rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.