My advice is if you have not bought the CPU then don't, it will not be a good choice for gaming. The CPU will not support overclocking, the mobos you have to use are expensive, compatibility issues will be more prevalent and the RAM will be limited to 2133 MHz. You can get much more for the same money.
http://www.cpu-world.com/Compare/498/Intel_Core_i7_i7-7700K_vs_Intel_Xeon_E3-1275_v6.html
Xeon Build
PCPartPicker part list:
https://pcpartpicker.com/list/r2KZVY
Price breakdown by merchant: https://pcpartpicker.com/list/r2KZVY/by_merchant/
CPU: Intel - Xeon E3-1275 V6 3.8GHz Quad-Core Processor ($362.40 @ Amazon)
Motherboard: Asus - E3 PRO GAMING V5 ATX LGA1151 Motherboard ($144.99 @ Amazon)
Memory: GeIL - EVO POTENZA 16GB (2 x 8GB) DDR4-2133 Memory ($121.99 @ Newegg)
Total: $629.38
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-10-05 10:29 EDT-0400
i7 Build
PCPartPicker part list:
https://pcpartpicker.com/list/vC2Rr7
Price breakdown by merchant: https://pcpartpicker.com/list/vC2Rr7/by_merchant/
CPU: Intel - Core i7-7700K 4.2GHz Quad-Core Processor ($319.88 @ OutletPC)
CPU Cooler: Deepcool - GAMMAXX 400 74.3 CFM CPU Cooler ($21.18 @ OutletPC)
Motherboard: Asus - PRIME Z270-A ATX LGA1151 Motherboard ($144.99 @ Amazon)
Memory: GeIL - EVO POTENZA 16GB (2 x 8GB) DDR4-3000 Memory ($143.99 @ Newegg)
Total: $630.04
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-10-05 10:27 EDT-0400