Did you buy that new MOBO yet?
I can confirm that this card works without any modifications:
https://www.amazon.com/gp/product/B07VZZ11GB/
I'm running two of these for the same reason you would. Lack of PCIE 16x ports.
Something like this https://www.amazon.com/JESOT-Controller-Express-Expression-Profile/dp/B07VZZ11GB/ref=sr_1_1_sspa?dchild=1&keywords=sata+controller&qid=1598381807&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyUlg4VTNKQzQ0WjBZJmVuY3J5cHRlZElkPUEwNzI4ODE2MUtGSEk0T1JPNjQ3NiZlbmNyeXB0ZWRBZElkPUEwNjY1NDQ4T1NHTkM2VVhZWjZEJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==