Thanks Stork, I have just managed to replicate your hector build while running El Capitan.
Clover would have been an hurdle too high to face alone, I am lucky enough to have a network specialist living in my place for the holidays.
I never managed to create my Unibeast installer with the copy of Mavericks that I still had on an hard drive and finding El Capitan proved to be difficult too.
Since the build with the Z87 UD3H I waited too long to download El Capitan from the Apple Store, I was stuck at the message that Sierra was not compatible with my new Mac Mini Core 2 Duo which is running with El Capitan too.
The person I bought it from on eBay was not even knowing which OS was installed on his machine...
I was not too keen to wipe the hard drive and start from Mavericks while safekeeping my latest jobs on an external HD with Time Machine thought it would certainly have been the better move.
Everything went absolutely fine until the installation of the GTX 750Ti, starting up the computer while disabling the GPU was an issue, in the Clover options we found that the line Boot Args had to be modified like this : Boot Args:kext-dev-mode=1 dart=0 -v
This left us with the possibility to install the Nvidia drivers specific to the build number of the machine.
Since this installation the Nvidia updater replaced the driver twice, the latest updates from the Apple Store was worrying, I had to reconnect the display to the HDMI port of the motherboard to avoid a black screen and no booting.
I will be cautious with any future features from the Apple Store.
Thanks again for your complete step by step tutorial especially with this specific configuration, my first search was including my i7 4770K processor and the H97N Wifi and the process to create the USB drive was not as clear as yours.