Dell, Inc. Sells Bad Motherboards and Will Not Replace Internet

Yea you could have extended your warranty and you would still be covered. 8 months is typical for a mobo. Plenty of time for dust and hair to get stuck in the fan or heatsink. They are like engines and they get hot and burn up if they are not taken care of. I'm a field tech and I see it all the time. Computers filled with dust and tucked into small cabinets where they get hot and cook themselves slowly until one day they quit. I have informed every customer that they need to ensure adequate ventilation and prevent dust from accumulating in the chassis, heatsinks, and fans. This info should be distributed by Dell to each customer I think. Then maybe the computers would last longer and customer satisfaction would get better. But then I might be out of a job! lol

You payed for a warranty period of x years. Did dell cover your hardware within that product warranty period, Yes. Did dell do what you payed them to do which was to cover and replace faulty hardware within the warranty period you paid for yes. Do parts go bad spontaneously, Yes. Did it fail within you warranty period, doesn't seem like it, You filed a report with the BBB to have a dell tech resolve your issue within dells policy, And without a warranty you would either have to purchase the part or if possible extend the warranty, So he was doing his job and Dell Responded to you BBB report
Simply put part failed out side of warranty period which can happen and without a warranty a part cannot be replaced.