Question Newly built pc won't boot, case parts work with psu cap 12 pin cord on but nothing works when 12 is connected to mobo

Oct 10, 2020
I have anew pc that I just put together ( After assembly it's not turning on. I have checked over 4 times that all the cables are in the correct spots, tried reseating my stick of ram, tried putting that stick of ram in both of the two slots in the mobo in case it wasn't in the correct one. The cpu is in the correct direction - I followed the whole match the arrow thing. My case power button isn't popping back up right and I thought maybe that was it, but after connecting the reset button to the power pins to use that as a power button instead, there's still no difference. Both the 8 and 12 pin psu cords are plugged into the mobo. When trying to turn it on, absolutely nothing starts, no fans spin, front usb ports do not light up. However, if I take the 12 pin connector out of the cpu and put the psu tester cap on it, then my case fans start spinning and case usb ports light up.

Does anyone have any other ideas of what to do/check, or run into a similar problem?