Why does Space Marine 2 crash during dense Tyranid battles?

Facing thousands of Tyranids was unsettling because the game would just crash to the desktop randomly. I first tried Auto-Overclocking in the BIOS, but it made things worse—crashes went from every two hours to every thirty minutes. I then opened the GamePP BIOS Load-Line Voltage Adjustment Guide, bumped memory voltage from 1.35V to 1.38V and set VCCSA to 1.22V. MemTest86 showed errors dropping from 8 to 0, while AIDA64 measured VRM temps at 62-68℃ and CPU-Z confirmed the 1.22V VCCSA.