I couldn't add more RAM because my board was from 2006. Max RAM was 4GB.
But I managed to tweet the memory timing settings a bit (2.5,3,3,7) and got the system running back up to performance again.
Then stuck a Geforce GTX 980Ti in it together with a Radeon HD8490, and the system is going along quite fine.
Confirming that 1950x/x399m is working fine in Windows 7 x64.
If some one interested I have solution.