Thanks for the advice.
I've tried one stick at a time in both slots using each stick, as well as swapping sticks. Didn't work at first, then I reset the CMOS (shortening the pins) and reseated the GPU, and that seemed to get my computer to show display. The computer is running at a degraded...
I've come back to this post to say that I've swapped out the MOBO (Gigabyte B450M DS3H Wifi), GPU (ASUS GeForce RTX 4070 Super Dual OC), and PSU (EVGA 850 G5) and my computer is still not turning on. I am now getting one long beep followed by three short beeps, followed by a very long beep...