I suspect if the cpu had any bent pins it would behave strangely for a long time now, which is not the case. Actually, it has not been removed or touched in any way, to cause issues because of a bent pin.
I troubleshooted a bit further.
F7 BIOS version has issues with XMP profiles as it seems.
F6 seems more stable for my Haswell i7-4790 cpu.
Following further troubleshooting with F6 BIOS, it seems that once the memory is configured with the XMP profile (2133Mhz), the M/B by default will set the vCore voltage to 1,24volts, which is way too high for my cpu.
It also pushes the memory voltage above 1,5Volts, while the vendor specs are for 1,5Volts.
Thanks to Intel's XTU (downloaded from Gigabyte's website), I was able to extract some more information.
Once the vCore voltage is set to auto or normal, the M/B will introduce a vCore offset of roughly 0.05 Volts, pushing the vCore from approximately 1,177 to 1,24 volts.
What I did:
I set the BIOS to the below settings and for the past last day, the system seems stable.
Memory Voltage: 1,5 Volts
vCore offset: Using the XTU utility I set the vCore offset to 0 (zero), and now it is running at 1,67~1,77 Volts.
Ran benchmarks without any issues.
I need to monitor the system for a while and see how it behaves.