AMD has two methods of locking the shader count on all of their recent GPUs. The first one relies on fuses inside the GPU, or on the substrate - a mechanism similar to Intel's multiplier locking. It is not reversible as far as we know. The second mechanism is the one we are interested in, AMD can configure the VGA BIOS in a way that it disables extra shaders, in addition to the ones disabled via the on-die fuses. This method is mostly used to create engineering samples or reviewer cards that match the target specifications. Usually production cards come with the shader count configured in the fuses, so that it can not be changed.You can check out the guide over here.
Apparently currently shipping Radeon HD 6950 cards from all manufacturers - which actually are all the same card with different sticker - have their shaders locked via the BIOS method, so we can exploit it easily.
AMD Radeon HD 6950 can be modded into a Radeon HD 6970
Posted on Monday, December 27 2010 @ 19:31 CET by Thomas De Maesschalck