Trying to overclock i5-4670K on MSI Z87-GD65

[Psyrion]

I recently purchased a new build:

Intel Core i5-4670k
MSI Z87-GD65
Noctua NH-D14
G.Skill Sniper C9 DDR3-1866
Corsair 650W PSU
NVIDIA GTX760 (MSI TF)
Samsung 840 Pro SSD
Corsair 600T Silver

I've already put the system through initial stress testing, and so far, it's stable at stock speeds with XMP enabled. I'm running into trouble though getting even a modest overclock (4.0/4.2). I'm aware of the heat and voltage issues with Haswell, but I'm seeing instability and I'm a bit lost with the newer options for voltages. Thus far, I've ran stable for 2 days at 4.2 GHZ at 1.22 Vcore, but after another STOP x0000124, I'm somewhat concerned. Any help at all would be greatly appreciated, especially from anyone with the same board as mine.

 

[kiezz]

theres a voltage called cpu input voltage that should be a minimum of 1.8v but if left on auto may be under that and causing instability,
some people claim to have run this as high as 2v for stability but i run mine at 1.85v and 4.4ghz stable the information i gathered was 1.8v is what intel say should be stock but i think some motherboard manufacturers keep it lower to decrease the heat at stock levels,
i think 4.2ghz at 1.22v is a good chip if stable, it takes me 1.27v for 4.4ghz