The above 2400 Mhz RAM suggested by The Paladin fits the build perfectly.
Even though Seasonic S12G-550 is good quality PSU, it's also fully wired and you'll get a good deal of headache with cable management. Here, i suggest that you go with Seasonic G series PSU that too is good quality PSU but it is semi-modular (to ease the cable management) and is also cheaper than S12G series.
pcpp: https://pcpartpicker.com/products/compare/gYMFf7,xVkD4D,DPCwrH/
You can go with G-450 if you like since the total wattage of your PC is 300W and 450W PSU is more than enough for it.
Full build with G-450 and matching white PC case.
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel Core i5-7500 3.4GHz Quad-Core...