Most boards these days have custom port plates. Pop out the old one, pop in the new one. Look at the mounting points (called Standoffs) and make sure you have the same number of them as you do holes in the board, and that they look like they should line up. Instal the board, and the mounting screws should find the hole as long as the mounting points line up.
Some cases have integrated mounting points (raised spots rather than standoffs) and if you have a board that would short to one, you'll have to figure out how to isolate that point (electric tape usually works.
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