Q:

Is it possible that AC mains (UK ~230V 50hz) could cause micro stutters under load in modern PC's on potentially noisy home sockets? 

I am experiencing machine stutters on my PC, after changing every single component 3+ times (every component, yes) and reinstalled operating system over multiple different disks.  Yet, they still persist with a sufficient power supply.  All drivers reinstalled. 
These stutters usually present themselves during processing, i.e. playing a game, or watching YouTube in a web browser for example. 
So is it possible—in a situation like this—that AC mains (UK ~230V 50hz) can cause micro stutters under load in modern PC's with potentially noisy mains in a home? 
See https://youtu.be/PY5QyRKK0IM

A:

Short answer: no
Long answer: The PSU converts the 50/60Hz AC into a near-perfect DC, with the remaining ripple being well above (orders of magnitude above) a few Hz.  You could of course use an 48VDC PSU and 4 car batteries, but I am convinced, you'd see the same stuttering. 
It is much more likely, that the stuttering is part of an interaction between software components, most likely some drivers, or just the hardware not being able to perform the tasks fluently.