that guide is not correct. dont flash a 6970 bios. especially on these cards, i have 2. they are non-ref and no bios switches, easier to brcik as no backup bios...
firstly let me say however this does not work in all cases, i have an older batch GB OC 6950 that unlocked but a newer batch one i bought since then did not (it flashed but shaders didnt change)
so what you need to do is this:
1- get gpuz and use it to make backup of bios.
2- then open it up in RBE (radeon bios editor) and go to 'additional features' tab change option 6950 -> 6970 for increase shader count. then save as new named bios rom file.
3- make a dos bootable usb (or whatever media) with atiflash.exe on it and the new modded bios file from step 2, assuming there is only one card execute following command: atiflash.exe -p 0 newromfile.rom
(this guide may help with this step :
http://www.techpowerup.com/forums/showthread.php?t=57750)
4- assuming step 3 worked and it says it flashed then you have chance of having extra shaders available on next boot. reboot and open gpuz to see count - 1536 is unlocked , 1408 is stock locked
5- to get lower mem clock you need to use ati tray tool, with that im able to run whatever i like. no other program can do this. at moment i can run 2 cards at 920/450 (1 card can run higher (upto 950)but i have two)
please ask if you have any more questions
these are great cards, and very quite, VERY! the best bit for me. hopefully you can unlock your shaders too.
this is my guide i just wrote for you now, not copied.
this is my btc address 1HS5Brzcsh7XkJn566XYbvfpa2JuBRBdss