Hi JinlaiZhu and Welcome to the Forum
At first start your system goes thru a POST (power on self test) where the system interrogates what hardware you have and other parameters that will allow a successful Boot to the OS. When it interrogates your RAM it goes thru a sort of training program to ensure SPD values are safe to continue. The system may restart several times for a fraction of a second or may shut the system down if you have a mismatch or null recognition of SPD (Serial Presence Detect)
Ensure your Bios and chipset are up to date.