I have been seeing reports that some are and some aren't. They are taking steps to stop the practice, even with reference cards (if you can even find them). Non-reference cards can also be unlocked, but not by flashing them to a 6970 bios. Even reference cards are better off unlocking the shaders in this other method, because it doesn't change any timings, voltages, fan profiles or anything else that is different with the 6970 that could harm a 6950.
As you can see by comments in through the post that a lot of people are not getting more shaders. This is due to some putting in read only bios, and others have laser cut shaders. If you go to the last post in that thread, you'll see a link to another site who followed my directions, and even found ways to bypass the read only bios, but their methods are not for the faint at heart.
As far as the risk goes, as long as you don't go to the extremes of unlocking the locked bios, it's fairly low risk, but there is risk. If things don't go right, most the time you can flash back to the original bios (make sure to save it). If your card ever faultered, as long as it can be used in a limited form, you should be able to flash the original bios back and it's unlikely they could tell anything had been done to it.
The instructions in my guide work for 1GB cards as well.
A lotta ppl on the BF3 forums are talking bout 6950s, what do you think about the 830 MHz 1GB from XFX?
Theres an 800 MHz, Im talking about the 830 MHz XFX 6950 1GB
Is that flashable? and does it actually perform like a 6970? Because I wanna make sure I know what Im talking about, I dont wanna tell ppl to flash to 6970 if its not something thats easy to do and stuff, it should be fairly easy, Im good at explaining things, but if its really complicated and stuff, then yeah...
The guide I posted doesn't turn cards into 6970's. It unlocks the shaders and leaves everything else as it was. 1GB, 2GB, reference or not, they are all changed so their shaders are unlocked. Unfortunately, some of the manufacturers are locking their bios. Some are cutting shaders. At this point, i can't tell you which will unlock or not. It seems to be fairly random.
Now once the shaders are unlocked, you can use MSI afterburner to overclock as high as you want after you unlock MSI afterburners limits.
If you unlock the shaders, it runs just like a 6970 at it's given clock. If you overclock the unlocked 6950 to 880/1350, it runs like a stock 6970 with the same clocks. It pretty much is a 6970, but with 6950 clocks when you first unlock the shaders. You can use overclocking software, like MSI afterburner to clock it to 6970 clocks or higher.
This method is a lot safer, as some 6950's can't handle the voltages and other timings that the 6970 has.
The other method is a little easier, but only works on reference cards. The other method has had reports of peoples card going bad within a month or a few months of use. This is because you are using different timings and voltages that the 6950 wasn't designed to handle.
The method in the guide is safer and works on non reference cards, including 1GB cards. It does include more steps.
Neither method works all the time, and lately, I'm guessing less than half will work.