Motherboard Issue?

[Ishenferi]

I just got my PC parts, and while trying to put it together, I noticed it wouldn't turn on. I assumed it was the PSU, and got a replacement right away. Same thing happened the second time, and now I was sure it was motherboard. I did a little googlefu, and saw a thread about jumping the power button with a flathead. Low and behold, the motherboard powers on. It seems to stay on (About five minutes so far as I write this.) but if I power it off, it stays off. Is it defective or what? I want to know if it's safe before I put any other pieces into it. 

[Wouterrinos]

2 minutes ago, Ishenferi said:

I just got my PC parts, and while trying to put it together, I noticed it wouldn't turn on. I assumed it was the PSU, and got a replacement right away. Same thing happened the second time, and now I was sure it was motherboard. I did a little googlefu, and saw a thread about jumping the power button with a flathead. Low and behold, the motherboard powers on. It seems to stay on (About five minutes so far as I write this.) but if I power it off, it stays off. Is it defective or what? I want to know if it's safe before I put any other pieces into it. 

the on switch seems to be defective, not the motherboard.

[minibois]

If it doesn't turn on at all when using the regular method (AKA: the power button on your case) the problem might lie in the connectors for the the power button. I think that cable is together with the other F Panel connectors on your motherboard (typically in the bottom right corner of your motherboard).

Check with the manual to see if everything is plugged in correctly.

[Ishenferi]

I never tried to actually plug the connectors in though, I just have everything laying out of the case. Would you think it's safe to actually put everything together?