Sofos1990 from Gigabyte OC Lab team did a nice X99 OC guide. We wanted to share it in full.
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With every new line up of motherboards from GIGABYTE, an OC Guide is made to help the users push the stock limits of their systems. X99 series is no exception to this rule. Coming straight from the OC Lab, here is the GIGABYTE X99-OC Guide made by the famous Soffos1990.
Features

OC PCIe Switch:
Allows the user to disable individual PCI-E slots. This is especially useful for PCIe diagnostic when it is difficult to remove the PCIe cards with cooling apparatus installed on. Also, you will notice that there are 4 LED lights, one for each PCI-E slot. If the PCIe card installed in the slot is working without a problem, then the LEDs stays on.
OC Ignition:
Provides power to DIMMs slots, PCIe slots and peripheral devices even when the system is off. This feature is a GIGABYTE exclusive and provides many hidden benefits to users. First of all you can test not only the PSU to make sure it properly works, but also any voltage modifications on your graphics cards, water cooling systems, case mods and fans (Virtually anything that requires the board or PSU to provide power to can be engaged). It is especially useful during cold bug situations when you need a fan to run 24/7 to keep condensation at bay. It also can be used to provide continuous power to the PCIe/PCI based RAM cards that lose memory when they are powered off.