do you have by any chance aorus 1080ti extreme? i know one user having exact same issue like you. he had tv connected to the card along with monitor, we never actually pin point whats causing the issue but he suspect it happens cause tv is plugged in and that causes some kind of conflict.
it may also be problem with ur PSU as others point out, never ever take crap PSU and pair it with high end GPU/CPU, u will have only headaches.
if you limit ur boosting to ~1800mhz and 0,8xx mV, no need to lower the power limit, on such low voltages, you card cannot pull more then ~150-180w, try benching with core clock on 1700mhz @ around 0,800mV and see if u get same performance issue then, if it not happens, it may really be PSU issue.
Last edited by Zfast4y0u; 03-21-2019 at 03:50 AM.