Asrock Z87 ex4 and i7 4770k, can't maintain above 4.2. Temps fine.

For one, you are using a guide that is not for your CPU.
2nd, It is recommended to not go over 1.3 V on air cooling, and 1.3-1.35 V on Haswell with water cooling. These chips run hot, and the more voltage you feed them, the hotter they will get.

I suggest you reset everything to stock bios settings, and try again. Really the only things you will ever need to change in order to overclock a Haswell CPU is the multiplier, and voltage. No need to mess with anything else, as it does not have much (if at all) of an effect on overclocking. Reset to defaults, set voltage to manual 1.2 V (do not use adaptive voltage when finding your overclock, and do not enter an offset), and start to raise your multiplier slowly (starting at 40-42, where you feel comfortable starting) until you reach instability. If instability occurs, add 0.025 Volts, until stability is reached (keeping that 1.3 V limit in mind since you have an air cooler.)

If wanting to use adaptive voltage for less power consumption at idle/low loads (it made a whole 3 watts difference for my computer, but allowed for lower temperatures at idle) it is best to find the manual voltage needed for your overclock first, and then to change the voltage over to adaptive once you find the correct settings for your CPU. Changing to adaptive might cause a few issues though, as even with stable settings, i found instability with my system and needed to add 0.010 volts to what was needed for the manual voltage overclock.

**Edit: Once the desired overclock is reached and the system is stable, you can then try to lower the voltage slowly (if you want to). This is a long and tedious process, as instability can occur at any time, and stress testing over and over to verify the CPU is stable with the slightly lower voltage is very time consuming. (I was able to lower my voltage from 1.23 V down to 1.223 V and remain stable at 4.4 GHz without an issue. Not much of a change in voltage, but it did lower the load temps by 1-2 Degrees.)

Last but not least, the stress testing and stability programs that i recommend using. I am not at all a fan of Prime95, never have been, never will be. ASUS Realbench (http://rog.asus.com/rog-pro/realbench-v2-leaderboard/) and AIDA64 Extreme (http://www.aida64.com/downloads) are the programs i use.

*ASUS Realbench is by far my favorites stress testing/benchmarking program. It uses real world applications to test the CPU and GPU in your system. This will give you a good idea of what kind of temps you can expect during rendering, image editing, h.264 encoding, and multitasking scenarios. The built in stress test will help to ensure overclock stability by using these real world applications to stress the CPU and GPU for however long of a duration you select (up to 8 hours). The only thing they could do to make this program better is to add temperature monitoring of components. When using Realbench, i monitor my CPU temperatures with RealTemp, and verify the voltage with CPU-Z.

*With AIDA64 you can get those same unrealistic temperatures that occur in Prime95 by stressing FPU, if that is really something you want to do. You can simply just stress the CPU to see what your load temperatures are without AVX instruction sets.