That kind of constant turning on and turning off can damage the fragile wafers of chipsets and CPUs in your PC. This might be the sign of a failing power supply.
Two things you need to check:
1). On your motherboard, check that the POWER SWITCH (PWR SW) and RESET SWITCH (RST SW) are correctly aligned and not slightly dislodged from their required spots.
2). After turning on the PC, go directly into the BIOS and turn on the failsafe defaults. Then, turn the PC back on and go into the BIOS again. Go into your monitoring area (hardware monitoring or voltage monitoring) and check that your voltages are AS CLOSE as possible to your required voltages.