Dell studio 540 power supply connections

[Jboundary]

Hello,
I just connected a replacement psu for a Dell studio 540 PC. The comp. Is stock and I believe there is only the the 3 connections but the monitor is saying there is no hdmi connection from the computer which there is. Any utube instructions out there I can follow?

 

[davcon]

Nothing to do with power supply connections btw.
Unless you have a discrete gpu card that require psu pcie 6pin power.
Unplug your video signal cables and monitor power cable and power/plug up again.