Update 0.6-188@201230 fails the startup overclock (not super clear on what exactly but it attempts to set something to -1000 and fails during the console startup routines.) It tries to mine but crashes shortly after Phoenix Miner starts. Falling back to 0.6-185@201230 without changing any other setting solves the problem; rig is stable under this version (0.6-185@201230).
Running an asus mining b250 know-it-all with NVIDIA cards, using eth pill on 4 of them. Problem also occurs on another single card computer running a 1080 using ethpill, not totally sure if ethpill is to blame.