Hey OP how are you doing? I've been watching this for almost a years now from many gaming forums with people complaining about this very issue.
I've read a lot of posts from people with your setup with stuttering problems and no software/OS/Tweak/Newer Driver has worked.
It's frustrating and there is a thread on the Geforce forums discussing this issue:
https://forums.geforce.com/default/...h-fps-drops-since-windows-10-creators-update/
It's one of the largest threads on their forum with over 4k replies. None of which have an answer. A lot of good ideas and tips I've even picked up on. Very informative if you have the patience.
However, and please forgive me as I didn't read all 6-7 pages, do you also try to OC your CPU to 4.8GHz - 5.0 Ghz as well? That too seems to be a common theme be it being returned to stock clocks or not. The 8700k is either delided or delided and OC to or close to 5.0Ghz.
There are, however, 2 possibilities that haven't been properly tested.
Possibility 1
Part 1
Reinstall Win10
1706/1709/1803 and install
Geforce 388.71
Use DDU to uninstall win10's Geforce drivers.
As this is the driver before the Mitigation Spectre update driver from Geforce. I say do a reinstall because it's not clear if their mitigation actually uninstall when you uninstall drivers.
Then see if it's smoother.
Part 2
Someone posted that updating to
RST 16_0_2_1086 (ONLY)
fixed the issue. Check for your chipset 1st to see if compatible.
However, this helped fixed the stutter as the issue wasn't the CPU/GPU nor Ram. It was the drivers in relation to win10/SSD. As the game swaps for data from the SSD caused the stuttering and frame rate drop issue and this particular driver fixed it. Even though the person posting that said they had newer RST driver.
Possibility 2
Put some sort of fan on your motherboard vregs/mosfets closest to your cpu socket.
Edit:
Almost forgot. Many have claimed that going back to win10 1607 fixes the issues. But you cannot update win10 1607 or else the stutter issue returned.
Edit:
Something else I'm reminded of. I've also read that those who upgraded from a 900 series to a 1080/ti seem to experience the problem. I've not read any post with those with a 1070TI, for example. As that is the 'newest' Pascal offered. I haven't seen , with consistency, that the 1070TI is also as plagued with stuttering issues like the above mentioned cards. Although that doesn't mean they don't exist.