Following the GeForce GTX 460 1 GBs, we’ve decided to take a look at the Radeon HD 6850s customized by AMD’s partners. They give a comparable level of performance to the GeForce GTX 460s and give good gaming for a decent price. They are however considered to have lower overclocking potential, something we’re going to check.
The Radeon HD 6850s are based on Barts, a GPU which is a sort of low-cost version of Cypress, used in the Radeon HD 5800s. A few small improvements have however been made, especially in terms of tessellation performance and support for DisplayPort 1.2 and MVC hardware decoding, the format used for 3D Blu-rays.
Barts is made up of 224 vec5 processing units (1120 ‘cores’) divided into 14 blocks, two of which are disabled in the version used for the Radeon HD 6850, bringing the number of vec5 processing units down to 192 (960 ‘cores’). The processing units are supplied by a 256-bit GDDR5 memory controlller, which has been simplified to reduce costs and which hasn’t been designed to clock very high.
You can find more details on this in the Radeon HD 6870 and 6850 test
and more recent performance measurements in the GeForce GTX 560 Ti test