Check Motherbaord Warranty
You mention the machine is about 3 years old. Check the EXACT date and the motherboard on ASUS site. Many of their motherboards have a THREE year warranty and you may be able to get it replaced for free. You will need to do the ASUS RMA and return it to them.
If it is still under warranty and you get it replaced then you can either keep it as a "just in case" or flog it on eBay.