i5-4670k Overclocking: Help Needed

[nemtrac5]

Trying to overclock my i5-4670k, I set it to 1.2v at 46 multiplier and it started to boot then crashed, so I upped the voltage to 1.25 and managed to get into windows but then it crashed when running prime95 blend. Right now I'm getting a stable 50c-60c degrees at 1.25v and 40 multiplier. I'm wondering if prime95 blend mode is fine for testing as well as if I should up the voltage/multiplier keeping in mind I want the processor to last as long as possible.

(Edit): Pictures of overclocking programs: http://imgur.com/kiA0FMx

GPU: Asus GeForce GTX 770
MOBO: Asus Z87-PRO ATX
CPU: Intel Core i5-4670k 3.4GHz
CPU COOLER: Phanteks PH-TC12DX
PSU: CORSAIR HX Series HX850 850W
CASE: Fractal Design Define R4 Black Pearl
HARDDRIVE: Seagate Barracuda ST2000DM001 2TB Serial ATA Hard Drive
RAM: Crucial Ballistix Sport 8Gb
OS: Windows 7

Also wondering about overclocking my GPU. The Asus is known for good temps and cooling, but I didn't think overclocking a GPU would be as safe (I have the intel tuning performance warranty). It is currently clocked to 1.11Ghz.

Pictures of the build (without aftermarket cooler - the aftermarket is on for the overclocking now): http://imgur.com/jMd5S2V,qUjWsFw,KpGbR8Q,j342UtT,R63WidD,869JCw4,EY6fzbp,KorjWAf#0

 

[masmotors]

i have same cpu and i cannot goover 4.5 crash even at that 4.4 and down is a ok i have mine st 4.3 @1.15 volts i like the temps there i have also tried @1.20 @1.19 and others just going up or down by .005 but i find 4.2 and 4.3 is enough for anything at stock it games about the same i just like it overclocked

 

[nemtrac5]

i have same cpu and i cannot goover 4.5 crash even at that 4.4 and down is a ok i have mine st 4.3 @1.15 volts i like the temps there i have also tried @1.20 @1.19 and others just going up or down by .005 but i find 4.2 and 4.3 is enough for anything at stock it games about the same i just like it overclocked

Well, I know I can increase the voltage and can overclock higher than what I currently have as long as the temperatures stay sub 80/90 and can try to keep the voltage the same and increase the multiplier. I just didn't know if someone could give me a estimate on where the cutoff point would be or what voltage I should look for.