That build is ridiculously priced, plus there's many points where it's got very poor component selection. You'd actually see worse performance (as a gaming rig) that something that costs less than half the price - think i5-6600K + 1080.
*The 5820K is not really suited for gaming. The additional cores are nice & all, but at the (significant) expense of clock speed - which can matter substantially in games.
*That's a completed overkill motherboard, and amount of RAM (again, for gaming)
*I'd hate to think how much these places attribute as a cost for Overclocking - something these 'boutique' builders rarely get right/stable anyway.
A quick crunch of the numbers, and you/I/anyone (paying full retail/consumer prices) could build that rig for somewhere in the $3k range. Would I recommend it, even at $3k? Absolutely not.
You're essentially paying a $2,000+ premium for overclocking (again, no guarantees it'll be stable) and for warranty/support (note, not return shipping though). Is that warranty/support worth $1,500+? I highly, highly doubt it. Lots of negatives out there about Ironside.
There's really no valid argument to spending more than ~$1,500 to $2,000 on a gaming rig itself. Peripherals etc will be on top - but as an example: $2,300 including monitor:
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel Core i5-6600K 3.5GHz Quad-Core Processor ($229.99 @ Newegg)
CPU Cooler: Noctua NH-D15 82.5 CFM CPU Cooler ($88.49 @ Newegg)
Motherboard: Asus Z170-A ATX LGA1151 Motherboard ($150.99 @ SuperBiiz)
Memory: Corsair Vengeance LPX 16GB (2 x 8GB) DDR4-2666 Memory ($71.89 @ OutletPC)
Storage: Samsung 850 EVO 250GB M.2-2280 Solid State Drive ($94.99 @ B&H)
Storage: Seagate Barracuda 2TB 3.5" 7200RPM Internal Hard Drive ($66.89 @ OutletPC)
Video Card: MSI GeForce GTX 1080 8GB Video Card ($669.99 @ SuperBiiz)
Case: NZXT H440 (Matte Black/Red) ATX Mid Tower Case ($109.99 @ SuperBiiz)
Power Supply: EVGA SuperNOVA P2 650W 80+ Platinum Certified Fully-Modular ATX Power Supply ($98.68 @ Amazon)
Operating System: Microsoft Windows 10 Home OEM 64-bit ($83.89 @ OutletPC)
Monitor: Asus ROG SWIFT PG278Q 27.0" 144Hz Monitor ($659.99 @ SuperBiiz)
Total: $2325.78
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-07-14 11:16 EDT-0400
I'd look around for a local store who would be willing to build it for you if you won't / can't yourself - but it's really not that difficult.