pc not booting up

[alihaider741]

i have cm 750w gold full modular power supply, z390 d motherboard.

sometimes when i push the power button only the rgb rams lights turn on no cpu cooler and power supply fan turns on.

it happens sometimes and mostly when i push the power button for long for shutting down.

i want to know which of my pc component is preventing my pc from booting up. 

i will be very thankful for your help

[Spotty]

Moved to Troubleshooting. Please don't post the same topic multiple times across different subforums.

[alihaider741]

actually i dont know if this problem is associated with power supplies or motherboards forums.