A very honest and thorough reply #14 from terry and tbh it is what I should have said in my reply #2
Not going to bang on about it as it would be closing the gate after the horse has bolted but five golden rules for a novice to follow before building a new computer are;
1: Do plenty of research on the do`s and dont`s.
2: Ensure compatibility for all parts.
3: Read and understand all installation manuals before starting.
4: Ask for help from someone who has upgrade or build knowledge, this includes posting on a forum such as GTG.
5: Always do a barebones set-up outside of the case on a non conductive surface such as the MB box first, this will identify any item that may have been DOA before it has been placed in the case where an incorrectly placed stand off or an incorrect power connection can cause a short and damage one or more components.
Other than what terry has suggested above all that I can suggest to see if some thing else is causing this is 1: confirm that the PSU still works by completely disconnecting it from the MB and then do the paperclip test. 2: remove the RAM and see if that changes the behaviour.