Look to be sure that you used the proper amount of motherboard mounting stands and that none are shorting out.
If you didn't bench test it on cardboard , take the MB back out of the case and strip the parts off of the MB and bench test every part to be sure everything's good.
Be sure that i7 is seated properly
My brand new custom PC that I built yesterday turns on the fans spin lights come on then it just shuts down no beeps or nothing the specs are:
CPU: Intel Core i7-4790K 4.0GHz Quad-Core Processor
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler
Thermal Compound: Arctic Silver 5 High-Density Polysynthetic Silver 3.5g Thermal Paste
Motherboard: Asus Z97 PRO GAMER ATX LGA1150 Motherboard
Memory: Kingston HyperX Fury Black 16GB (2 x 8GB) DDR3-1333 Memory
Storage: Crucial MX200 500GB 2.5" Solid State Drive
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive
Video Card: MSI GeForce GTX 980 Ti 6GB Video Card
Case: NZXT H440 (Green/Black) ATX Mid Tower Case
Power Supply: EVGA SuperNOVA NEX 650W 80+ Gold Certified Fully-Modular ATX Power Supply