I had a similar case when I was prepping an old computer I had for someone and they brought in a video card (I gutted the computer's). It wouldn't boot. No beeps, nothing. Took out the video card, gave me the video card failure beep. Took out the RAM, it beeped at me.
Found out the BIOS I put in there didn't like newer cards. I had to rollback to a version that did like it.
That's the only thing I have to suggest, but considering this is a fresh build, you can't update BIOS until you can actually get into it... so if you have any old video cards lying around, see if the computer boots up on that.