Do you trust Newegg more than Gigabyte who manufacture that motherboard or Tom's that reviewed it? If not, then please read this review http://www.tomshardware.com/reviews/z77-express-ivy-bridge-benchmark,3254-18.html
The reviewer wrote "We still get the same single x16 to twin x8 slot conversion from the processor’s sixteen PCIe 3.0 lanes, and the third slot is still a four-lane PCIe 2.0 product of the Z77 Express PCH. Gigabyte further warns that all three of the board’s x1 slots are disabled whenever a PCIe x4 (or larger) card is installed in the bottom slot, since only four of the chipset’s eight lanes are available for expansion. The aforementioned drive controllers, plus a network controller and PCIe-to-PCI switch, consume the chipset’s other four lanes."