Tone down shadows probably to just PCSS or High. Environment at max is also very taxing at the highest setting with not a ton of visual improvement so I turned it down so I could enable HBAO+ ultra. Should be able to get HBAO+ Ultra and one of the better antialiasing at 1080 with that rig.
I'm on a 980ti at 1440p though. Those are my settings for locked 60, save for AA, which I had to tone down to FXAA, probably going to try injecting SMAA when I start playing again shortly. So a 980 at 1080 ought to be able to tweak a setting or two higher than me I'd wager.