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 to the CPU while loading it with 100% stress for wPrime 1024M 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 4790K clocked @ 4600 MHz 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 4790K 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. Very few coolers and kits can actually manage a Core i7 4970K @ 1.3+ Volts / 4600+ MHz temperature wise well enough.

Core i7 4790K and 1.3 Volts on the CPU (we measure package temperature). I'd be OK with this temp for a long term overclock, as long as it remains at ~75 Degrees C.

Extended Tweaking

Since this 360 mm solution harbors some extra cooling capacity I extended overclocking to higher voltages as well. 

The above numbers are just for reference only e.g. how does a 4790K behave with increased voltages at a 4600 MHz clock frequency. We can run the unit towards 1.40~.145 Volts on the processor (which is a lot for this CPU!). At this stage the system still boots and can finish two wPrime stress runs. Typically at 1.35~1.40 Volts and a good enough processor, you are in the 5 GHz range (if your CPU is capable).