@fulltrashcanchannel957
Make sure that the 24-pin connector is plugged in entirely, as well as any CPU power cables that are located on top of the motherboard. They all have to be slotted in. Also, if something fits somewhere, doesn’t usually means it belongs here, so make sure you haven’t accidentally connected GPU’s 6-pin into CPU’s 4-pin :)
@a-person1624
use old power supply (if it boots up with the old one then there is a problem with new one) be sure cables are fully connected check HDMI cable to your monitor is correct check your monitor itself is correct
@theCrawg
Try unplugging one cable at a time and se if it posts, and hopefully it's just one of the cables and not the whole PSU that's faulty. This happened to me once and it turned out one of the SATA-cables were faulty.
@Kampfpener17
Try different GPU if it does not boot up with a different PSU
@aaronfowler7706