I don't believe there is a BIOS update to "unlock" the remaining GK110 SMXs on GTX 780s... So as such there won't be one for the 690.
Nvidia just released a whole brand new card for that, being able to unlock those would be shooting themselves in the foot, and also risky to the end user because those SMXs are disabled because of bad yields. If I'm wrong, feel free to link it, I'd be especially interested to see it.