Why won't the OS start?

Question

ubuntu

We assembled a new PC, took the hard drive and power supply from the old one. When you start the OS, the computer reboots, when you install the OS or when you are in the BIOS, the screen turns off after a short time (as if it is not connected to the vidyuhi), the keyboard does not respond. Launched ubuntu from a flash drive - it works. Please help me to solve this problem.

Answer 1

overheating, radiator blade, incomplete connectors, swollen electrolytes, other hardware problems, errors on the screw ... there are
a lot of options.
clairvoyants do not live here - according to your descriptions, no one can say what ...