Question Computer does not connect to Monitor, no lights shown on keyboard or mouse

[KKlevverr]

I have a relatively new self built pc, but now it won't connect to my monitor. I recently unplugged everything and messed with my RAM as it would only show 8 of 16 gigs, and when I went to plug it back in to my monitor it says no signal. Any help is appreciated.

 

[JohnBonhamsGhost]

are other lights, peripherals, USB ports receiving power?
and post your complete system specs.