I built my first pc recently, and not too long after I was done, it started turning off then back on without any warning. At first I thought it was overheating, but after checking temps, its 30c idle, 45ish while gaming. I checked all the parts and did alot of what I can without buying new parts. My main suspect is motherboard because I bought it used. I'm not sure though because some days itll work all day and some it wont stay on longer then 10 minutes. Can anyone give any pointers?