I too came from EVGA, truth be told I think the bios on the EVGA boards was better, easier to work with and less confusing. Right now I am running similar processor, cooler and motherboard as you but I am experiencing high temps no matter how I look at it. Running 174x23 with a 1.35V at 4GHz I idle around 40c and load high 70's to low 80's. This has me confused as I am coming from an EVGA X58 3xSLI ( 1st gen board ) Core i7 920 and a H50, with that makeup I had to run 201x21 1.4V idled low 30's load at low 70's. Higher voltage but got lower temps????
Answer to your question, the recommended steps for 4GHz is to just up the voltage once the system BSOD's after that its just epeen. Adjusting QPI settings allows you to lower your CPU Vcore but it will increase the NB temp most likely so you need to keep an eye on that if you decide to mess with it. I'd suggest looking through the EVGA froums regaruding OCing questions as I find their guides to be more helpful. I've been browsing this forum for awhile now and find it to be very poor compared to the EVGA forums.
My R3E is pretty good board but like I said, the bios is pretty poor, alot of options and I am sure for the enthusiates like ourselves it will come in handy. I just find it to be disorganized, I like the layout better on EVGA boards.
I may try your method as I am underclocking my ram right now due to the 174x23, will try dropping it down to 21x201 and see what I can get. My main reason for upgrading was because everything was on sale and I'd already had the board, processor and ram for over a year. But I was hoping that I could hit an OC of 4GHz with being able to run a lower voltage at lower temps. The exact opposite occured.... Lower voltage at higher temps.
Intel Core i7 5930K @ 4.8GHz, Asus Rampave V Extreme U3.1, Kingston HyperX Fury 2666MHz 32GB DDR4 ( 4x8GB ), Nvidia GeForce Titan-X SLI, Creative Labs E3 USB Soundcard, Samsung 950 Pro 512GB M.2 NVME, Corsair AXi 1500i PSU, Corsair 900D, Corsair K95 RGB Keyboard, Logitech Proteus Core Mouse, Acer Predator X34 @ 100Hz, Sennheiser Gamer Zero, Windows 10 Professional