to boot you will need a Drive - HDD, SSD - even external will do it.
To be sure if it starts set the start SOUND FOR THE UEFI - was some keyboard reset key kombination.
Normally with PSU and MB is not enough - you need a RAM at least 1 Module!
SO RAM + MB + PSU = STARTS
TO have Video - you need the video card connected too.
You may check this app https://play.google....ac.NIGHTMAREPRO - is free