I have/had the UP4 and a 4930K I could not get over 4.1-4.2 GHz stable because of improperly working LLC. VDroop was exceedingly bad. The same processor with a P9X79 WS went to 4.5 GHz with ease. The UP4 is good for stock clocks, but not much else.
OP, your original build looks fine to me, if a bit plain. By plain, I mean I build configurations like that all the time for a "generic" gaming computer. Big, clunky, mostly empty case, unused PCIe lanes, small SSD, big, slow HDD. You have the budget to have a bit of fun.
This is my "over the top" 2K mITX build for those who detest multi-card setups (your 650W PSU would struggle with an overclocked 770 SLI system anyway):
http://pcpartpicker.com/p/3cyel
CPU: Intel Core i7-4770K 3.5GHz Quad-Core Processor ($309.99 @ Newegg)
CPU Cooler: Corsair H90 94.0 CFM Liquid CPU Cooler ($79.99 @ Newegg)
Motherboard: Asus MAXIMUS VI IMPACT Mini ITX LGA1150 Motherboard ($219.99 @ Amazon)
Memory: Crucial Ballistix Sport 16GB (2 x 8GB) DDR3-1600 Memory ($149.99 @ Micro Center)
Storage: Samsung 840 Pro Series 512GB 2.5" Solid State Disk ($389.99 @ Best Buy)
Video Card: EVGA GeForce GTX 780 Ti 3GB Video Card ($669.99 @ NCIX US)
Case: Fractal Design Node 304 Mini ITX Tower Case ($79.99 @ Newegg)
Power Supply: SeaSonic 650W 80+ Gold Certified Semi-Modular ATX Power Supply ($100.98 @ SuperBiiz)
Total: $2000.91
(Prices include shipping, taxes, and discounts when available.)
To me, the OS is an assumed/absorbed cost, much like a monitor or a keyboard; that would bring it over 2K.
No legacy parts (disk drives, hard drives) and a clean, modern aesthetic. Not to mention properly small. This PC would be a complete "sleeper." No flash/bling, all go!
This is definitely not for everyone though, and requires the right taste. It definitely has high performance per liter while missing the mark on performance per dollar.*
*You can of course substitute a much cheaper SSD and a HDD to cut some cost, drop down to a GTX 780/GTX 770 or i5 4670K, go with an CM 212 Evo, etc. Just be careful with power supplies in that case.
Good luck on your decision.