New psu doesn't work with mining rig/mobo but old one does

[beastly4k]

I upgraded from my Evga 750w gold to a Evga 1600w plat.

My old psu powers the rig fine. The new psu will only kick it on for a second and shut off even with bare minimum mobo/hdd only plugged in.

The new psu came with a testing adapter and I used that and it stays on so I don't think it's my outlet.

The mobo is Maximus Vi hero. I have a btc 2.0 on the way but I'm worried I'll have the same issue. Any advice would be appreciated.

[Vann]

Make sure the 8-pin CPU connector is plugged in to the motherboard from the PSU.