Erratic shutdown on boot up.

[RushIsRight97]

I had a perfectly working pc until I got and installed a new cpu/motherboard, updated the bios and reinstalled windows 10. Whenever I try to boot up, the pc may: (1) fail to post, (2) fail to boot windows, (3) crash on login, (4) crash less than one min. after login, (5) boot up and work perfectly until I myself shut it down later.

 1 - I have stripped my pc down to only one RAM, keyboard, SSD to troubleshoot and it acts exactly the same.

2 - I tried different ram to same effect.

3 - PSU was bought new 2.5 months ago (pc can sometimes perfectly function).

4 - No capacitors look damaged. 

5 - CMOS battery was low then replaced

6 - CMOS reset

 

PC gives no beeps or errors, it just resets or shuts down without warning. Anyone know what I should do?

CPU/ i5-2500

MB/ Intel DQ670W