You're not going to go for Custom water cooling loops, are you? If so, then why not buy the Obsidian 750d instead of the 900d. As for RAM, 16GB is quite overkill. But, if you're going to play a game while copy-pasting files, web browser(s) open, Windows explorer, Yada yada, then I think you may need 16gb of ram. Here's a recommendation for a motherboard, and ram:
Motherboard: ASUS maximus VI Hero LGA 1150.
It comes with some very nice software, easy to use bios, great for overclocking (though not the best) reliable, cost effective, above-average onboard sound, and a nice color scheme.
Goes with the color scheme, reliable, CAS 7, overclocks like a champ; can achieve DDR3 2400 with CAS 9, has more room for upgrades, so you won't have to toss 4 ram sticks away when you decide to upgrade, cost effective. Besides, LGA 1150 platforms aren't meant for 4-way sli/ quad channel memory. They don't have enough lanes to power those beasts. If you're going to go for more multi-tasked and sli-based operations, I'd go with the following:
Performs better than 4770k in multi-tasked application, better in multi-core operations, inferior, but only by about ~5-8% in single threaded applications, does not have heat issues, therefore, better overclocking. Do note though, the X79 chipset is on its last legs. It won't last very long, If you're gonna upgrade to haswell-e or roadwells. Another thing, haswell refreshes are coming in 2014, so hopefully those will fix the temperature issues, so you won't have to de-lid you cpu, and will feature functionality on the lga 1150 platform.
More overclocking oriented, solid, up to 4-way sli. Punch in the gut though, when it comes to price.
Another few to consider:
You can also wait a few days for the release of the ASUS Rampage Black edition. Looks promising.
Those not only come in different color schemes, but also utilize the quad-channel benefits you get from LGA 2011 boards. Here's an important equation to remember when it comes to RAM's performance: (CAS/Clock Rate)2000. The lesser the number you get, the less cycles the ram has to do, resulting in faster response times.
Well, that wraps it up for all the info I can give you for now. I'd appreciate some feedback from not only you, but from more users aswell. Last thing: Try checking out PC part picker (.com). What it does is, you select the parts you want, save as a list (create an account for this), and it automaticalls shows you where you can buy those parts for the cheapest. Usually saves me about ~100$ in a full fledged build.