A:Answer I hate to say it, but you may be locked to 1st and 2nd gen Ryzen on that board.
https://www.dell.com/support/home/en-us/product-support/product/inspiron-5675-gaming-desktop/drivers
These pre built PCs are tuned to work a certain way with certain hardware, however, with just an extra $100 to $140, you can drop a new motherboard in there with your Ryzen 3000 CPU. You can buy a Ryzen 3000 CPU and a B550 and toss the Dell OEM motherboard. Just a thought.