I would go with the ¹ ASRock B450M PRO4, you could try the ² ASRock B450M Steel Legend

¹ https://www.vuugo.com/asrock-motherboards-B450M-PRO4.html?tracking=5108053939762

² https://www.canadacomputers.com/product_info.php?cPath=26_1207_1205_1505&item_id=136298

And the best option would be, to call vuugo for availability or even back order the following board.

MSI B450M MORTAR

I been digging through these, just remember the x470 often has higher specs for power and mem speed and usually better VRM than B450, but cheaper versions can be marginal. The older x370 the top ones were good enough they didn't even change some of the better ones on new x470 versions. Generally a board good for OC will have better VRM. VRM is not everything its really more important if you OC a lot, or big OC an 8 core is going to need more power and might be much for a 450 or lesser board. Most gamers don't need a lot of cores. Watch the Buildzoid video on x470 boards to learn more, however remember he is all about MAX OC power not other options and likes the best vrm boards mostly because of that. The Asus tend to have a nicer bios for OC stuff, but asrock msi and gigabyte have some good boards too. The x470 asus prime pro has sinks on the vrm and turns out to be pretty good at OC, but has no led for post problems and its not cheap, it is right in the middle with pretty good hardware and bios but not a top gamer board with all the bling. I am looking at that or the strix only because I figure a better board will take a better cpu down the road. Buildzoid even admits to overheat the asus vrm he OC'd the processor to a voltage so high he would never actually run that, and the prime is a mid board not high end hero. He really leans on things, got it to shut down at 125C after 45min stress testing. I'd say any of the b450 with good reviews and features you want should work, especially if they successfully OC on them (reasonable oc) without bios problems. I like Asus a little better for bios and mem speeds but they don't discount as much either. Other budget high rated gaming boards should work great for you. Look carefully at the features though and get what you want, and don't count out a Nvme prices are getting good and they are much faster than sata.