I've played a few games, issue seems even worse my RPD is here https://drive.google.com/file/d/1r-ukS\_G2GB4pWXYBdQ3uLHss7BafK3TM/view?usp=share\_link
Yeah. That is really odd. Every second, there is a spike for a few frames. Those spikes are ruining your frame rate - if they weren't there you'd be running nicely. I can see where you've tried different frame caps, and that didn't make a difference.
I suspect something external is stealing CPU cycles? I dunno - this one's weird. Do you have anything running which does stuff once every second?