Would work but not best way. That CPU needs better MB with better VRM section, some x470/x570 MB would be more suited.
If 3800x is much more expensive than 3700x then 700x would be better option. For pure gaming, even R5 3600 would give you almost same performance with that GPU or let you have better GPU with so saved money.
I totally agree with Mike here. I would also give the same recommendations:
1. The Ryzen 7 3700X is a much better value than the Ryzen 7 3800X
2. You will need a much better motherboard to complement such a high-end CPU. X570 would be preferable but an X470 may work.
3. If this is a gaming build, you might want to go for a Ryzen 5 CPU and get an RTX 2060 Super (or higher) instead. Even then, I would still treat it with a better B450 board than the one you picked. At the very least the B450 Aorus Elite, but preferably something like the B450 Tomahawk or B450-F Strix.
Note: Not all B450 and X470 boards are compatible with 3rd Gen Ryzen out of the box, so be careful when purchasing.