If you were under warranty, you should've gotten the replacement mobo from Dell... and if not... any replacement mobo with the same processor socket would've done fine.
The whole way of going about dropping money on a custom built PC... is that typically... whatever money you drop as your base... THAT is like your bed frame. Now, you can change your mattress every year or two... and that's cool. That's the way it should be done. You get the nice leather-bound hardwood beauty put together, and you change out the mattresses when need be. That's the difference. Buying these micro machines is like buying an IKEA bed. Now you'll get the enthusiasts, ... with the water cooling, ... the overclocking... the built in S&M straps on the posts if you will... but really... that's tasteless crap. You don't need a waterbed. You don't need the straps, etc... etc... Keep it simple, classy, and balls-to-the-wall (pun intended) sturdy.
What I'm getting down to here, are the details of a good machine. A good machine, hands down, and I'm afraid I'm really stubborn on this... is: Silent, Powerful, monochromatic hardware, and no LEDs. You don't need bright, you don't need bells or whistles. You need quiet, badass, seamless BD playback with great audio... and for it to be capable of something monstrous - like the equivalent powering on your AVR when some ignoramus was using the TV speakers. This is how my machine operates, ... where I do what I do day to day with it... and then when the mood strikes... it's my recording studio. You know what I mean?
Now even if you don't have an alternate use for a PC like that (recording, gaming, graphic design, ripping), I'm sorry... I STILL can't feel an argument against owning a powerhouse that's capable of everything. To me it's the equivalent of carrying a great pocket knife - which every man should have on him - period.
That said, that's just if you're using a PC. I'm an all or nothing kind of guy - who's drinking scotch so please forgive my tone. If you're not a PC person, there's no shame to not go PC at all, and instead drop your money on a great OPPO or integrated amp you've been missing instead... There's no shame in Quality over Quantity. PC is a quest for both, being humble and buying all of your media, is great!
I guess just being an IT guy and someone who builds quality machines... when I see someone's playback or system hang, stutter, or give any kind of lip, instantly... it's infuriating - like why aren't we just watching or listening to this on a dedicated source if your shi*'s going to behave this way... kind of thing.
It's really rough. I wager we all have the trouble every day of looking at your budget, looking at gear, looking at your budget, looking at your wife, looking at gear...
God help us. All I can say is the one lump investment ... it tears the strip from your wallet like a bandaid, and I haven't had a regret since I did it.