Here's what I got with my air cooled W3520 on the 760. The vtt was stock at this speed until I upped the uncore. I found stability at 17x with +.05mv, and 18x with +.1mv I was using IBT 2x 10 passes to test the settings out before launching into prime95 blend, it hiccupped on the 2nd IBT, so I upped the vcor 1 notch and the vtt +.025mv just to be sure. 19x wouldn't boot at this setting using 2:8 on the mem.
Remember e-leet seems to show .09v higher than set and measured with a DMM, the rest are very accurate