If you are not planning on upgrading your GTX 730 in the near future to a more powerful GPU card than Black Zion answer is fine.
According to this PSU Website : PSU REQUIREMENTS - RealHardTechX , The Nvidia GTX 730 needs a minimum PSU of 300 watts for system usage.
Plus the Ryzen 7 1700X has a TDP of 95 watts.
But if you are planning of upgrading your CPU and especially your GPU card in the future, and if you can afford it, I would suggest to purchase a High Quality Metal Rated (Platinum, Gold, Silver, or Bronze) PSU with at least 700 watts or more.
That way you will know that you can upgrade to one of the more powerful GPU cards or CPUs plus any other hardware that uses higher wattages without any worries.
I purchased, at the time, 8 years ago a Corsair Gold rated AX850 PSU (at that time a very expensive PSU. cost over $250.00). I have a fully loaded Computer with external and internal hardware connected and my very old PSU still is supplying enough power without any power issues. In those 8 years I have upgraded my GPU card and CPU several times up to the present Nvidia GTX 1070 and AMD FX 8350.
When I purchased my PSU at that time, eight years ago, 850 watts was way overpowered for what I had installed. But I read it is best to purchase a High Quality PSU with plenty of wattage in case I needed to upgrade my hardware.
