Before the arrival of its new entry level graphics cards, AMD is bringing out the Radeon HD 6790, an additional mid-range model. Positioned exactly opposite the GeForce GTX 550 Ti, it should have a fairly straightforward performance advantage. It remains to be seen if following in the footsteps of the Radeon HD 5830 will truly make it a worthwhile model...
AMD has based development of the Radeon 6790 around a cut down version of Barts, the GPU used in the Radeon HD 6800s. The aim is of course to be able to give as many outlets as posssible for Barts GPUs which couldn’t make the grade as Radeon HD 6850s or 6870s. This LE version is scaled down just as the Cypress LE was for the Radeon HD 5830:
- 30% of processing units deactivated
- 50% of ROPs deactivated
- Higher TDP and core clock
As AMD has decoupled the ROPs from the memory controllers in its GPUs it can deactivate ROPs without affecting the memory controllers. The ROPs do however take up a lot of memory bandwidth and also represent an important pathway for this memory. Deactivating half of them therefore does have an impact on the GPU’s capacity to exploit fully the memory bandwidth made available by the 256 bit Barts bus.
To recycle a maximum of GPUs with significant current leakage, or which require higher GPU voltage, AMD and its partners have based the HD 6790 on an HD 6870 type design, better adapted to the potential load than the Radeon HD 6850. This results in a bigger card and of course higher energy consumption than the HD 6850, which however gives higher performance.
This Radeon HD 6790 therefore has a good few built-in disadvantages and won’t make much of an impact unless it gives very value. AMD will have to make a real effort given how complex the card’s design is. How does €130 look?