You do not need the adapter. The motherboard you chose only needs the 4 pin CPU power connector.
And you wouldn't need the adapter anyway. Using the 4 -> 8 pin adapter will not increase the amount of power you can pull from the CPU power plug.
That motherboard doesn't have the 8 pin connector , but my first choice was a Gigabyte board that did.
My current PSU is barely enough for what I have right now according to newegg's wattage calculator.
It calculated 479W and my Fortron is only 500W.
If I buy a bigger PSU I would like to buy the one with the proper connectors, otherwise the adapter should be fine.
My question is:
If I buy a Gigabyte board like this
, which kind of PSU will have the proper connectors?