6pin to 2x 6pin splitter extra wire just means more voltage drop. And if you’re using a peripheral connector to PCI Express adapter then be sure to plug each of the adapter’s peripheral connectors into a separate PSU cable. They gave you two peripheral connectors for a reason.
Connect any graphics card to a single 6pin to 2x 6pin splitter PCI-Express Power Cable. The 6+2-pin male connectors offer maximum versatility. The IRQ address is a signal sent from a device to the central processing unit (CPU) specifying an event, such as an audio signal starting or stopping. The I/O receives and transfers data to and from a device such as an MP3 player.
Similar to the older standards like PCI and AGP, a PCI Express based device (like the one shown in the photo on this page) physically slides into a PCI Express slot on the motherboard. The PCI Express interface allows high bandwidth communication between the device and the motherboard, as well as other hardware. While not very common, an external version of PCI Express exists as well, unsurprisingly called External PCI Express but often shortened to ePCIe.
6pin to 2x 6pin splitter, being external, require a special cable to connect whatever external, ePCIe device is being used to the computer via an ePCIe port, usually located on the back of the computer, supplied by either the motherboard or a special internal PCIe card.
Generally, PCI Express refers to the actual expansion slots on the motherboard that accept PCIe-based expansion cards and to the types of expansion cards themselves.
PCI Express has all but replaced AGP and PCI, both of which replaced the oldest widely-used connection type called ISA. While computers may contain a mix of various types of expansion slots, PCI Express is considered the standard internal interface. Many computer motherboards today are manufactured only with PCI Express slots.