Core i7 4790K OC at 4600 MHz 1.3 Volts

Now we up the ante. Understand that 1.3V and higher voltages are the levels where Haswell processors get into serious problems due to the aforementioned heat-spreader versus TIM design applied solution from Intel. We now set the Core i7 4790K @ 4600 MHz and apply 1.30 volts on the CPU while loading it with 100% stress for wPrime to run on all available CPU threads three times.

Core i7 4790K OC at 4600 MHz 1.3 Volts - IDLE 

Below, you can see the IDLE results with the Core i7 clocked at 4790K @ 4600 GHz with 1.30 volts on the CPU. Again, the results are the IDLE temperatures thus you are in your desktop doing pretty much nothing. 

Core i7 3770K OC at 4600 MHz 1.3 Volts LOAD

Now we'll be testing the temperatures under fully threaded stress. If we set the overclock at 4600 MHz and configure CPU Voltage at 1.3V, these are the results.  

The temps normally rise above and beyond 90 Degrees C for a lot of heatpipe based coolers, which is a definitive no-no. As you can see, we have dangerous temperatures for most coolers. Very few coolers and kits can actually manage a Core i7 4970K @ 1.3+ Volts / 4600+ MHz temperature wise well enough.

The Noctua NH-L9x65 is having it rough, seriously rough up-to a level we would not recommend you to overclock with this particular processor and voltage. But this was to be expected.
 

We run wPrime 2 times, at the last run we measure the peak temperature which was 84~85 Degrees with a Core i7 4790K amd 1.3 Volts in the CPU. The overall temp is not recommended for long term stability, for that it'll needs to be below 75 Degrees C max.