Yes for non turbo, LLC will stabilize the Vcore. Your current 1.35 Vcore is probably only giving 1.28V under load, but with LLC you'll get that full 1.35V so you can drop Vcore down too if you turn it on.
I find it's good to turn LLC off for Turbo Boost enabled OCs because it'll run higher voltage at the higher speeds/lower voltage at lower speeds. Saves a few degrees C
I've tried hundreds of different settings to try and get higher but won't budge, I think I might have reached the hardware limit tbh, but I don't mind too much, I recently got a x58a-ud7 and am saving up for 980x, this is just my gf's computer, so she won't mind, I just couldn't help but try and get higher