Hey pal,
Did you find a solution for this? I have an almost identical system as you, same exact CPU (also overclocked @ 4.9Ghz) and an RTX 2060 (instead of a 2070) and I also suffer from the exact same issue you have/had (we are not that many with these symptoms). The performance is fine and what I would expect like 90% of the time, but the other 10% is heavy stuttering which drops me to single digits and all 6 cores shoot up to 100% utilization (it normally stays at around 50% average). I have screenshots that show an identical behavior:
Could it be something specific to the 9600k? I have tried everything short of going back to stock clock speed (which I'm seriously considering) but the fact that every single other game I have doesn't exhibit this issue makes me think it's simply FS2020.
Wondering if you found something? I haven't. Even potato low settings don't help. It happens less, but still happens.