That's good news, it's not the motherboard.
The first step would be to RMA the faulty stick of RAM and get replacements. Contact either the manufacturer, or the seller, and arrange an RMA. Once the RAM is replaced, we can fix the bitflips and other errors. I may need to call in the help of another expert when it comes to doing that though, it's not something I am comfortable with (yet) - I'm still undergoing training for that :)
Merry Christmas to you too. :)