Question Computer turns on for 1 second then turns off constantly

[J15C0D3R]

My computer has been turning on and off constantly by itself after I initially press the power button. The psu does not show any problems on my power supply tester, I had compared the readings with my known good psu and seen no difference. I do not know what the issue could be.

Specs:
Unbranded 1000w psu
8GB Kingston’s DDR3
I7 3700S cpu
Sandisk 480gb ssd
WD blue 500gb hdd
LG blue ray dvd rom
MSI B75A-G43 gaming mb

 

[Ralston18]

Make and model PC?

"Unbranded" PSU is a concern but if you were able to test the PSU and satisfy yourself that the PSU is functional - okay.

Wondering about thermal paste and possible overheating that shuts down the computer.

Any error codes or warnings in Event Viewer or Reliability History?

Doublecheck that all internal components are fully and firmly seated. Things do tend to creep loose over time due to heating and cooling.