Will try to answer your questions, but first a brief story of why.
I do IT for a private school, and we change out all of our computer hardware (laptops, tablets, desktops) every 3 years. Well the next change will be coming summer 2014. When we do this, we usually have no choice but to use the current OS at the time, which will me Win 8 (we are windows shop). So, generally we get a budget to build a PC so that we can start researching the new OS, new software i.e. Adobe CS 6.0 vs 5.5, Office versions and a whole host of other crap. Unfortunately, my team all has to agree on the hardware that we order for the most part, we are allowed Cases and Video cards of our choice. So hopefully this explains why some of it is not "ideal" and perhaps overkill.
Motherboard was the better of the two choices we had, while none of us are serious OCer's, Gigabyte does have an app called Easy Tune which quickly OC's your system to mild, medium or insane. I just did the mild one, and went from a 3.5Ghz CPU speed to 4.1. No, i didn't look at how it stepped up the RAM, OCing is just not my thing, but I figure as easy as the Easy Tune is, why not. The Thunderbolt is a nice feature, and I will give it a go down the road, but for right now it's just chilling there.
I didn't buy an extra internal drive because we all have the 1 TB Western Digital Black, and I have a 3 TB External USB 3.0 drive, so the 512GB SSD was plenty for me. Plus, other then my movies, I just don't have that much stuff.
As for the amount of RAM, it was more of a "Just because we can" thing. Our last system that we built had 6 Gigs, and I barely used that, 32 is just ridiculous, but again, why not?
Windows 8 is because we have to do research to figure out how we are going to deploy it to our users in a way that will work for them, and meet our guidelines.
Power supply was an experiment, yes there were others, but along with our CPU cooling solution, we thought we would try this just to see.
My case is a Antec Dark Fleet-85
it's huge, but air flow is great, and I have never had any heat issues with it.
CPU cooling solution is the Antec Kuhler H20 620
. We wanted to go with a different solution, but they were out, so this was a last minute decision and we thought we would try out the closed liquid cooling system. If it works, great, if not, we will find something else.