Server PSU not powering Motherboards

Recently had another buildout and the 1300 watt psu just wouldnt come on and isnt the first time Ive had this issue in a build.
B450 Pro Mobo and Evga 1300 Mining PSU

I stuck a $50 650watt psu that worked and a 24pin spillter to the 1300 and then they both worked. Is there something making the 1300watt not work with regular motherboards?

Ive searched tech help and youtube university (thats what I call YT as I have learned so many things) and not found any info on 1k and above PSU not working with certain mobos but I did find a work around with the 24pin splitter. Id rather just the 1300PSU work. Also had a corsair and another PSU over 1k watts just not power mobo on. I know to put the 8pin power in the right area, make sure the clear cmos isnt on, no standoffs touching mobo. Anyone share some wisdom?