Since ive been browsing these forums for a while trying to fix the onboard sound when my 770m is installed I thought I would share some of the steps I did to finally fix it.
After a few days of trying and probably 50 reboots I managed to get both the 770m and IDT onboard sound working at the same time.
While I might have been just luck as at first it was very unstable and would yellow screen randomly it appears to have disappeard.
Some of these steps were: (Windows 8.1 I don't know if these