Got a third 870 to play around with, L923 something. I'm at work currently, but before I left it was 25 passes into linX at 20x200 1.25625v vCore and 1.25v VTT, LLC on of course. I can probably go lower, currently I'm just trying to get a starting point. Lowest i've been is 1.2375v with 5 passes of LinX.

Screens later, this is so much better than my previous 860/870s, they all needed 1.37v for 4ghz, lol. IIRC, the 860 was L947, and the 870s were L018 and L021, very new batches.