Help refining overclock

[FL630]

So I think I've managed a stable overclock, but the voltage is a little higher than I'd like right now, so can anyone point me in the direction of how to make this a little more "long term friendly"?

I'm not sure I got the greatest of CPU's, I was really hoping for a lower voltage at 4.7 or in an ideal dream-world 4.8GHz. My mate got one of the magic "top 10%" CPU's so I feel hard done by not managing to match his 5GHz

Spec:
i7-4790k
Gigabyte Z97X G1 Gaming
16GB DDR3 HyperX Savage 2400mHz
Corsair H80i (temp until I install custom loop later this year)
EVGA Supernova G2 750W PSU

My BIOS changes are as follows (all terms are from my Gigabyte BIOS, naturally other brands call settings different things) :

CPU Multiplier: 40
Turbo Ratio: 47
Uncore Ratio: 40
Vcore: 1.325v
CPU VRIN External Override: 1.9v
Ring Voltage: 1.2V

K OC: Enabled
CPU PLL Selection: LCPLL
Filter PLL Level: High
CPU VRIN Loadline Calibration: Extreme
PWM Phase Control: eXm Perf.

RAM has XMP enabled and is running at 2400mHz which I'm happy with.

Temps during stress tests such as Realbench Benchmark (x5 cycles) hover around the low 70s.

I'd like to reduce my Vcore to 1.3v if possible, but I get BSOD's, could I lower it however and change any other settings to keep my required stability?

Where does one even start to make it a more efficient overclock.

Thanks,
FL630

 

[FL630]

Thanks chaps.

I'm OC'ing directly in the BIOS, wont use the crappy in-Windows OC tools which will just overvolt.

My CPU was made in Vietnam, not purchased from OCUK, so seem to be stuck with 4.7GHz. I can get it to boot no problem at 4.8GHz, but if you stress test it BSOD's at about 4-5 minutes, obviously no good.

Not had a chance to play with voltages as I've been busy with work over the last few days, but I will tomorrow.

I'm following some guides to make sure the CPU volts and clocks down at light load, but still goes up to 1.325v 4.7GHz and remains stable, that's the aim, feels a big one for a newbie to this sort of thing.

Temps at idle on a warm evening in a warm room, 27 degrees with fans at 600rpm, I'm dead chuffed with that.