Why is there a huge temperature gap between my CPU cores?

While exploring medieval villages, I noticed a weird divergence where Core 1 was 60℃ while Core 4 hit 86℃, causing 15-35ms frame fluctuations per GamePP. I first tried increasing the chassis fan speeds; while overall temps dropped by 2℃, the core delta remained over 20℃ per HWInfo64. I accessed the GamePP Hardware Control page and switched the pump mode from Silent to Extreme, forcing the speed to 3100-3300 RPM. The core delta converged to 5-8℃ per HWInfo64, and the pump stabilized at 3200RPM per GamePP Pump Monitor. Now it is set