Black screen

My PC was working fine, then I just start to get widows blue screen. So I let it do the troubleshooting and it restarted fine, a few mins later the same thing. I thought it was a windows problem so I reinstalled windows. It worked for about 30mins then blue screen again. But this time I just get a black screen. I replaced the power supply with a working one same thing. I replace the RAM, same thing. I even replaced the graphics card, but same thing. If I clear the COSMOS by removing the battery on the motherboard I can get into the BIOS, so I updated the BIOS to make sure that wasn't the problem. But once I exit the BIOS the pc restarr but then its only black screen again. I tried to boot to different hard drives (SSD's) But still only black screen. My only thing I can think of is that the motherboard is vaulty. But I'm not sure, the motherboard is only 2 weeks old.