Radeon 6850 might run fine with 6870 BIOS

Currently we are testing a handful of R6800 cards from AMD's board partners and we ran into a curiosity yesterday.

One of the 6850 cards we tested was showing above baseline performance, which made us wonder as to why and how that was happening at reference clocks. This morning we had an inquiry in our mailbox of that board partners with the report that the 6850 card they had send out has 1120 active shader processors instead of the 960 shader processors that should be active for the 6850.

This means that there are no laser cuts on the Barts GPU for the 6850, and that also means that it's likely you can flash a R6870 BIOS into the 6850. Now first off, if you decide to try that, you do it at your own risk, if things go wrong ... it's your loss and warranty does not apply.

Bare in mind that the R6870 BIOS will run the graphics card at 900 MHz and that is a critical point here, the PCB design of the 6850 is different and the cooling is not as good. You could of course lower the GPU clocks a little. Also the 6850 of course only has one 6-peg connector instead of two on the R6870. Still, the 6-pin 75W is a PCI spec not a treshold or absolute limitation.

All in all interesting stuff for the uber-tweakers out there. Oh and COULD is the keyword here okay ?

** update -- as it is right now looks like a BIOS update is not possible and that the extra shaders are dealt with at ASIC level.