I bought a Jonsbo C2 case, and a ASRock B450M Pro-F MATX board. The board is standard MATX size: 244x244. The case says its takes MATX 245x215! so doesnt fit :-(
Are there any AM4 MATX boards out there that are 244x215? Google is proving unhelpful.
That case really is a good one for mini-ITX boards because it will fit a triple-height GPU. So the double and 2 1/2 height ones, common today, will fit with good clearance for airflow into the fans.
If changing motherboard I'd suggest go looking for one in m-ITX size. These slim m-ATX are pretty poor looking bottom-of-stack boards, especially compared to most m-ITX that are very well featured with a cool-running VRM that is needed in compact mini-ITX cases like you're trying to fit one in.