I would check out the Super Sampling and Target Render settings, as well as any of the new blendy thing the Vive has (similar in concept to the Rifts ASW). Extreme levels of SS aren't needed 200% should be the max you put to as levels above this aren't really noticeable at all. Target Render Multiplier, I've read that it has little performance hits, so crank that higher and see if things get clearer.
I don't know, what you are referring to by "Target Render Multiplier", but the only two options important to get a clearer image and a bit of anti-aliasing is either in-game HMD resolution or SteamVR supersampling. With a frame rate target of 90 FPS and some headroom, 1.5 supersampling (in ED) or 225% resolution scale (SteamVR) is realistic for an overclocked 1080Ti. You need to turn most settings on low or med nontheless, keep texture quality on high, AA, bloom, DOF and motion blur off. It might help to set the process priority of ED to high.
With the December update to SteamVR reprojection settings are limited, you can only either activate always-on reprojection or interleaved and asychronous reprojection. The former provides some CPU headroom, but needs 90 Fps otherwise you will notice stuttering, the latter (in combination) will work best on weaker systems to prevent stuttering. But interleaved reprojection will reduce your Fps to 45 and interpolate the rest of the frames. I favour asynchronous reprojection only for ED, since it causes only a small performance hit, but smoothes out small framedrops below 90 Fps. You need an older SteamVR version, however. With the current version always-on repro in combination with motion smoothing might be a good compromise.