Just this week we tracked such FPS drops to something else. In one case is was W10's update sharing, the others were mostly HDD issues and a mismosh of other causes. If you believe it's the limit, you will have to ask the maker what that means. I've yet to find this makes any difference.
Read how to share the details at https://www.piriform.com/docs/speccy/using-speccy/publishing-a-speccy-profile-to-the-web
I was having fps drops from 60fps to around 15 for around 15 seconds in around 3 minute intervals so I opened up msi afterburner and found that the voltage limit went from 1 to 0 when I was having issues and I know it is not because of temperature because the temperature never got above 55c I've tried making sure that power and temp limit are not linked and power limit is set to 100% ps here are my other specs if you need them:
cpu: amd fx-8350
ram: hyperX fury black 16gb 1866
gpu: msi gtx 960 2gb
Thanks in advance
ps here is what it looks like the lag correlates with the voltage limit: https://imgur.com/a/TijOS