Motherboards in computers should easily last the lifespan of the computer which is around 10 to 12 years and after 10 to 12 years it's likely you'll be upgrading your computer to a nice new computer anyway.
I keep my desktop computer for only 10 years at the most unless a new processor or some other upgrade comes out that is needed.
By the time your motherboard needs replaced other things on your desktop computer will likely fail anyway and the parts will likely cost you more than the computer is worth and it's much cheaper to just buy a new computer.
I can buy a brand new desktop computer without the computer monitor on ebay for $250.00 and sometimes cheaper if I can find a deal.
At that price it's certainly not worth fixing my current desktop computer.