The drops seem associated with an increase in CPU fan speed, followed by the fan speed immediately dropping. I've done some analysis with MSI afterburner (see the pic attached). It seems that the CPU temps drop all the sudden, and this is associated with a CPU clock drop, i.e; framerate drop.
That is not CPU temperature throttling. Your CPU speed is being slam dunked to 800MHz which is indicative of Bi-Directional PROCHOT being activated. This is usually connected to the VRHOT line from your VRM. IOW the VRM / MOSFETs are getting too hot. Provide them better cooling and/or limit CPU power consumption through PL1 / PL2. While power throttling will reduce the CPU ratio it shouldn't be a whole lot if correctly set.