Why does ELDEN RING FPS drop from 60 to 30 during boss attacks?

During giant Boss attacks, my frames plummet from 60 to 30 without warning, making dodging feel like I'm moving through mud. I tried lowering all in-game graphics settings, but while I gained 5 FPS, the hardware-induced stutters remained. I used the GamePP Fan Curve Configuration Panel to force chassis fans to 2400 RPM when the VRM hit 80℃. RTSS showed frame times converged to 16-22ms, and AIDA64 confirmed CPU temps stabilized at 76-82℃, while HWInfo showed VRM temps dropped from 98℃ to 80℃.