Why is my frame rate jumping between 80-120 FPS in Gears 5?

When switching cover quickly in Gears 5, my frame rate bounces between 80 and 120 FPS—a total nightmare for a competitive shooter. I tried enabling PBO Enhanced Mode in BIOS; while max FPS increased, the minimum FPS actually dropped by 5 per RTSS, which was shocking. I used the GamePP Resource Scheduler to switch the game to 'High Performance' mode and set the core scheduling priority to 'Realtime'. HWiNFO64 showed core frequencies stabilized at 4.2-4.5 GHz, and AIDA64 confirmed CPU temps stayed within 65-72℃, making the experience buttery smooth.