Question New build/builder, no post.

Aug 19, 2019
Motherboard: ASUS Prime X470 Pro
CPU: AMD Ryzen 7 2700X
GPU: ZOTAC GeForce GTX 1070 AMP! Extreme
RAM: CORSAIR Vengeance RGB PRO 16GB (2x8) 3600MHz
PSU: Seasonic FOCUS Plus 650 Gold

Symptom(s): No post/video output/USB accessory power, despite all the decorative LEDs lighting up, CPU fan spinning, and GPU fans spinning at boot (then cutting off shortly thereafter).

Background: Finally broke down and splashed the cash on a decent rig, thought I did my homework but apparently I missed something. Attempted the build on Thursday, only to arrive at the symptoms described above. After some brief troubleshooting, I decided I'd have Amazon send me a new motherboard (same board), but alas. The symptoms prevailed. At this moment, I've tried a single stick of RAM in every slot, clearing CMOS, seating and reseating the processor, checking all relevant connections, and bench testing (think you guys call it breadboarding) outside the case. After some reading I determined that my RAM isn't on the QVL, but it sounds like that maybe isn't a huge deal, as very similar CORSAIR modules are on the QVL. Normally I'd assume something is going wrong between my graphics unit and the display, but the USB keyboard/mouse not getting any power suggests something different to me. Sorry to clutter the forum with a generic new guy post, but I am now at a loss. Any suggestions are appreciated.