How to Unlock HD 6950 to HD 6970

PogMoThoin

A few weeks ago AMD released the Radeon HD 6970 and Radeon HD 6950. Both cards are based on AMD's new Cayman core which is their first graphics processor to use a VLIW4 shader configuration.

Just like on all other similar products, AMD's two Cayman variants, called Cayman Pro and Cayman XT, are based on the exact same GPU silicon. The model variant a GPU chip becomes is decided after the die is produced, at some point before it is put on the card. Creating new SKUs from the same silicon by locking features has been common practice in the industry since at least the Radeon 9500 in 2002.

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.

http://www.techpowerup.com/articles/overclocking/vidcard/159

deconduo

Looks cool, but there are some problems. A lot of people are getting artifacts even at stock clocks. The lack of an 8-pin connector hurts, not enough power.


I'd guess its like unlocking cores, some people will get lucky and some won't.

Solitaire

IIRC AMD tweaked the GPUs to make a load of marginal dies capable of running as HD6970s, but then BIOS-locked them as HD6950s because it was causing too severe a shortage of HD6950s in the retail channel, screwing up pricing. Thus the BIOS lock.

Wonder if there's a similar exploit for reference-PCB HD6850s...

Overheal

Soooo... if you can make 6970s, a lot of them, why do you need to supply a bunch of 6950s?

Solitaire

Market positioning. Plus some of the last-minute upgraded cards could run all the SIMD clusters but couldn't do it at a reasonable enough clock speed or voltage without either stability or heat issues.

PogMoThoin

Overheal wrote: »

Soooo... if you can make 6970s, a lot of them, why do you need to supply a bunch of 6950s?

To completely control the market.
Nvidia have done this too, 5 years ago I had a 6800gs, it could be unlocked to 6800gt with Rivatuner. My 7900gt could also be volt modded to do 7900gtx clocks with a conductive ink pen that cost a fiver.

lmimmfn

usually the lower quality cards get "turned" into the lesser cards so chances are you wont get the same overclock as a 6970, but of course you could be really lucky. This is pretty cool actually, reminds me of my old 850 pro and flashing it to XT.

Makes me wish i had gotten a 6950 now instead of a 6970 lol. I think the memory chips are different and also the cooler, but could be wrong as ive no 6950 to compare against, but they are shorter cards.

roast

I was delighted when W1z posted that on TPU. I'm planning on getting a 6950 within a week or two, definitely going to try it out.