No POST 3070 RTX rig

[sabriel666]

https://pcpartpicker.com/list/TtzmMb
RTX 3070 (second-hand) - Asus B660M-A D4 Wifi - i5 12400F 2.5GHz - EVGA 650W 80+ G3 (second-hand) - Versa H18

 

I recently bought parts for a new build and built outside of case. Had no problems booting the first few times. Mounted everything except SSD in my case, managed to boot a few times and update the BIOS.  After some (unidentified) change my rig will no longer POST. My mobo buzzer (1 long + 3 short beeps) indicates an error with my GPU. 

 

Attempted re-seating the GPU. Tried with different GPUs (RX 480 and 1080 Ti) and PSU (also 650W) known to be working. Tested with single RAM. Tried clearing CMOS between different configurations. A colleague also tested the 3070 RTX afterwards and had no problems booting. 

 

This is my third build, but I felt some of the ports and f.ex PCIE slot were more hard/forceful than I remember. Could it be the PCIE pins are mashed or not seating properly? Any tips appreciated.