My computer is having some problems. Any ideas?

Hi, so my dad and I built my gaming PC together by buying all the hardware seperately. When we first completed my PC, it would turn on, but there would be no signal on the monitor. My dad thought it was either my video card that was broken or my motherboard. We tested both on different PC's and it turns out that it was my motherboard's problem. After two or three days of doing nothing with my brand new pc, I decided to give it another try. I turned it on and it turned on successfully. I've been gaming on it for about a month now with no problems, and now, my whole PC crashes. What happens is when I'm playing a game, my monitor goes black. My PC is still running because I can hear the fans still running. Now, the next few things vary.

Sometimes, I power on my PC and I get that same problem from when I first built my PC - No signal on my monitor.

Other times, my PC boots up for a few seconds and then the monitor goes black again.

Other times, I can boot up my PC fully, but after playing a few minutes of games, it does that same crash.

I will probably contact my motherboard maufacturer and see if I can replace it. But first, I want to know exactly what the problem is. My graphics card? My motherboard? My power supply? Or is it any other hardware that might be bad?

Thanks for taking time to reading this. I'm not that good with computers though so if you do use computer terms and think that a newbie won't understand the terms, can you please explain? I know what CMOS and BIOS is so if I have to configure something there, you can just say it, no need to explain what those are.

Thanks again.

Just return the motherboard to the maker and get it replaced. Most manufacturers have a RMA policy see if your board falls under that category.exezlabor