Shuttle has created a nice calculator to determine if the stock power supply will accommodate the components you might want to install in your new builds or upgrades. It will tell you if you need to upgrade the power supply to the 500W PC63J. Select the model, enter the CPU, Graphics Card, Memory, Storage Devices and USB Devices, you can predetermine what components to purchase for compatibility with the PSU.
Here is the link to the Shuttle Power Supply Calculator.
By the way, the PC63J 500W power supply will be compatible with the new J4 and H3/H7 models.