Jonathan268ll

new ram can still be bad, buy one stick used the cheapest used and 100%  (see that it works for the seller ) know it works and try that , any maby try changing sata cables and disconnect ssd/hdd it has happened one that didn't boot because of bad sata cable but happens super rarely

Check the manual and verify which slot you put just one stick of RAM into then do just that, only one stick.  Verify 24 and 4 pin power are correct at both the board and PSU.
Verify the input on your monitor is correct.  If you are using HDMI try the DVI instead and vice versa, just to eliminate the possibility that is bad.
After that, there isn't much else it could be...