Amd 6950 unlock.

There are many ways to damage a card like hitting it with a hammer but you probably didn't mean that.
Unlocking means to flash a 6970 BIOS. The possibility to brake the card is there, but very very small, and I don't know any way how you might be able to tell beforehand if the card is unlockable or not. You might search in forums to see if folks had more luck with a brand or the other, that's about as far as it goes.

Here, I think this will answer all your questions:

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

Remember, get a reference card, nothing fancy. Google the model number just to make sure.

You don't know until you buy the card and try to unlock, if it's a reference design most likely will let you unlock the locked shaders. Problem is, they are no longer available BNIB unless you buy one used. There's no way to brick/damage the card if you do it right and knowing what you do before flashing the BIOS.

Shaders unlockable 6950s:

1. Laser cut GPU core.
2. Bios flash locked, even hard mod will not help.
3. Combination of the above.

The left picture is a locked shaders count and the right is after shaders unlocked.

Ken 1649 and LAKings good advice.

One card to stay away from though it pains to say, is the Sapphire Dirt 3. There's been some cards that have gone out instead of Cayman chips like their supposed to be went out with Antilles chips. They were laser cut which disables the possibility of unlocking.

I'm not sure the exact reason for this. It could be shortage of Cayman and surplus of Antilles but a 6950 is supposed to be Cayman.

Anyway those who've received the Antilles versions with their Sapphire Dirt 3 GPU's have all been unsuccessful to unlock the shaders.

I would strongly suggest the Sapphire Toxic AMD 6950 over any other 6950 out there IMO. It's the safest bet and comes with the DUAL BIOS switch. One hell of a card.

Also last piece of suggestion, if you do go with a reference GPU, please keep in mind it may not be unlockable anyway. Odds are you will, but there have been some that couldn't.

If your honestly looking for 6970 performance and your not willing to take the slightest chance then please by all means buy a 6970. It's 100% going to give you the performance you want.

Vendors have been doing great sales on the 6950 due to the unlocking capabilities, but it's sort of a mixed bag. I'm speculating - the 6970 sales aren't as strong and their over stocked compared to the 6950's which are harder to find as they go quicker than a hot dog in a school of piranha.

I have a strong feeling they are starting to disable the shaders so their sales/revenue go higher and they can unload the 6970's before the next gen cards hit store shelves.

BTW, Zvejniex - Welcome to OCN

It does make sense. Only I personally wouldn't take the chance with my own money for the Dirt3 version, thus my advice was opinion with some fact. Only the Cayman versions of the Dirt3 unlock, none of the Antilles versions have. You know more than anyone I think that Sapphire are great AMD cards. Hence why I strongly suggested he go with the Sapphire Toxic.

I also fully agree with you about XFX unlocking possibility not good, if at all.

I gave the warning because in those instances where the card dosen't unlock you have an upset post where the OP was expecting it to unlock as if it was meant to be. Just warning him about some possible grief and gamble.

I know that a heavily over clocked 6950 even without being unlocked still can OC as high as an unlocked 6950. Great OC'ers.

I know your pulling my leg LA