Personally I wouldn't put a 5800x on a 450 chipset..
I had problems with 3700x on 370 chipset, so I purchased Asus Tuf Gaming x570 mobo..
The problems I had with the 370 was VRM's were not up to powering the 3700x, you could have the same problem with the B450..
If I were you get a B550 or better an x570 mobo..
AMD Ryzen 7 3700x, Asus Tuf Gaming RX 6700 XT, Asus TUF Gaming x570 Plus, 32gb G.Skill TZ neo 3600mhz, Samsung 980pro 1tb NVME, Samsung 970 EVO Plus 1tb NVME, Lian Li Galahad AIO 240mm, Antec Titanium 1kw.