Overall that’s a pretty good build you got there since you are only going to be doing Online TV, movies, excel matlab etc.
For what you are doing I don’t think overclocking will be needed. I mainly see overclocking for gaming.
Again, for what you are doing you doing I wouldn’t worry about SLI.
For Excel I would like a large monitor like a 22" or 24"!
If you are going to be using somewhat of a tv/htpc you may want to consider a tv tuner card. You can get a cheap one just for regular TV and use Windows Media Center. Netflix and much more build in.
I don’t think noise will be a problem.
Lastly, you may want to make sure you have room to expand on your system later down the road. For instance, you see a nice game and need a nice video card
That said make sure you have a large enough PSU that can handle add-ons such as hard drives and expansion cards.
Hope this helps!