Hi - the video lag/dropped FPS almost, even when opening the start menu etc seems to have disappeared. A new nvidia driver came out and I installed that, and I'm not sure if that's whats fixed it. I haven't been checking Latency Monitor, and I'm on the latest Windows Insider build at the moment - There's been no stuttering/audio pops etc. It seems my Sandisk SSD was faulty, although a part of me wonders if for some reason my old SSD was just incompatible with my PC's hardware - the issues seem to come round right about the time I built my new PC, and the SSD was only 15 months old at the time. I now have a Corsair MX500, which is supposedly one of the best SATA SSDs you can get.It's not clear to me what you might be referring to as far as video lag. Not responding to mouse input as quickly as you're used to or ?
As far as LatencyMon, I wouldn't be too worried if you're no longer getting the audio pops and dropouts. I recently installed a Windows 10 Insider build and ran a trace of my system. It was showing quite high DPC processing times for DPCs running on cores other than 0 and sure enough it was associated with ntoskrnl.exe. One took as long as 17 milliseconds which would normally be considered terrible and yet my system was running better than it has since the Spectre/Meltdown updates last year. So I think Microsoft have done some tweaks regarding ISR/DPC scheduling to make better use of multiple processors in the Insider builds and I doubt LatencyMon is taking those changes into account yet - if ever they do. When I reverted back to build 1809 all my DPCs went back to sub-millisecond levels so if you're still using an Insider build it might be worth trying the 1809 build to see if your DPCs also become more reasonable.
One last unrelated question - there's currently a great deal on a G-Skill 3200mhz 16GB DDR4 RAM module - would you expect this to significantly improve performance over my current 8GB 2667mhz module? I do not do any video editing etc, just a light gamer (although when I do game, its usually the high end graphically intensive games), 4K movie watcher etc.
Lastly, thank you so much for your assistance. Truly, you have no idea how good it is to not have those DPC latency issues anymore. I no longer have to restart my PC 15+ times a day! :)