an X99 chipset on a motherboard can support up to 2 x 16 Pci-e express lanes for crossfire of two graphics cards.
Where as a 760G does not.
If an Amd cpu is used the supported HT speed on a X99 board is 2600Mhz basically 2600Mhz HT at 2600Mhz x 2 =5200 between the cpu and the main bus.
It supports more Usb port connection and will also have USB 3.0 port support. with USAP transfer speeds.
And more Sata ports are supported by the chip set also.
The board will be more stable when it comes to overclocking a cpu.
Plus you tend to get lot`s of overclocing features and options due to the x99 chipset, if you overclock.