what you ask is impossible.Fabric can not go higher than memory but i have run fabric up to 1900 testing fine and also 1.5v on b-die ram is fine,i a not sure where people come up with these things ,any back to game.
If you have IF at 1900MHz and RAM at 3800MHz then they're in sync. You're unlikely to make any gains pushing memory above 3800MHz because of the extra latency you get from having the memory clock higher than IF.