OK thanks. Was slightly unsure of the timings of building now, but as i'm not looking to upgrade for some considerable time I guess it's less of an issue.
I opened the MOBO box and noticed that the seal was broken, so will be sending that back to Amazon. Have ordered the B450m Mortar Max as replacement, not in stock at the moment; so if it doesn't come back - I can possibly wait until B550m. Will the B550m boards work with Ryzen 5 3600 chips?