Hi E_D, soory, question a bit unclear, post written late at night, lol!
The 290 have 2560 shaders. The 290x has 2816.
My first 290 unlocked smoothly (still have some issue with the Hynix modules that should OC well over 1500MHe, but well... wil star a thread about that).
The second one did not at the first attempt, but briefly showed 2816 (2 or 3 Windows start/shutdown). And then back to 2560.
I was wondering if it could be a bug of GPU-z.
One thing: the device ID did not change when I flashed the 290x Bios, I guess it should if the flash works fine, right?