In theory, you might be able to replace your board with an upgrade, but why? A new m/b will not change performance and if you do change the m/b, you will need to buy a new copy of windows as your OEM copy is married to your current m/b.
From what I have been able to find, your computer is an All-In-One model. The Dell website makes no mention of a motherboard upgrade, so I would imagine you are pretty much stuck with what you have.