Try deleting Intel XTU and/or Throttle Stop (or both if you have both instaled), I had this same issue on my asus vivobook (i5 7200u) and i was trying to fix it for the past 5 months (it started about a week after installing Intel XTU (undervolting)). Yesterday I gave up on this issue and deleted Throttle Stop (i switched from Intel XTU, becouse others said its better) and the problem is now GONE. I wanted to smash my monitor when i found this out, its the least obvious thing. Also my laptop power limit throttled even while using chrome to 0,36 Ghz and i was already considering buying a new computer. Basically, it was unusable.
Also if this worked for you, as it did for me, please make sure other people see it. And don't forget to update your bios.
I hope you see this and that it helped anybody :).