Question Hey guys, these past few days im trying to figure out what is wrong with my pc(boot problem)

[Mentalpig]

So it all started after i unpluged my dekstop pc from power supply and left it to sit for 24hours, after that when i turned my pc it boots up for like 20 seconds(black screen on monitor) then turns off for couple seconds and then boots up again(still black screen), i tried many different things such as removing parts and puting them back in, cmos battery change, bios jumper reset, maybe its psu? My fans are working though.
Im using h87m-e33 mb. With integrated graphics.
Psu: cori model:550xi, its old was using it about 6-7 years, never had any problems though.
Proc: intel i7 ( cant find exact number of model cause oc doesnt boot up)
Windows 10
Any solutions whats causing the problem?
Ps. Sorry if my english is bad.

 

[Ralston18]

PSU is a likely suspect.

Update your post to include full system hardware specs and OS.

Include PSU: make, model, wattage, age, condition?

When there is a successful boot look in Reliability History for error codes and warnings.