Question Motherboard only comes to life when 24pin connector is half in

Aug 25, 2020
I have a b365 pro 4 motherboard brand new all the parts im about to list are brand new i5 9400f processor 16 gb 3.2ghz ddr4 ram and a gtx 1650 super with a 600w evga power supply from best buy and i tested the psu with the paperclip test and it worked as expected but im troubled cause whenever i plug in the 24 pin connector my pc only comes to life when its half in the connector on the motherboard dont know whether its the motherboard or psu the led light on the gtx 1650 flashes when its half way in as if the power was pulsing from the psu and therefor it dosnt start up anything but the fans continually spin but the gtx 1650 led flashes please help dont know what to do