The processor supports up to 46 bits of physical address space and 48-bit of virtual address space. • The Intel® Xeon® processor E5-1600 and E5-2600 v3 product families and Intel® Xeon® processor E5-4600 v3 product families feature (per socket) two Intel® QuickPath Interconnect point-to-point links capable of up to 9.6 GT/s, up to 40 lanes of PCI Express* 3.0 links capable of 8.0 GT/s, and 4 lanes of DMI2/PCI Express* 2.0. It features 2 IMCs (Integrated Memory Controller), which support DDR4 DIMMs.
The implementation of a motherboard capable of running 4 x GPUs (Asus X99-E WS) depends upon the motherboard manufacturer.
I hope this helps,