Quad SLI on P8Z68-V/GEN3

Hello, I am wondering if it's possible to run Quad SLI on this board. It says it can on http://usa.asus.com/Motherboards/Intel_Socket_1155/P8Z6....

Can it really do it though at full speed, because 2 of the PCI express slots are showing some pretty low speeds. I realize that it couldn't do 4x PCI-E 3.0 since only 2 of the slots are 3.0. That makes sense, but not completely sure if it can do PCI-E 2.0 with 4 cards. Right now I have 2x 560 Tis. I was considering purchasing 2 more identical 560 Tis and a new PSU. My processor is a 3770k, so I'd think that I would meet the requirements. Help if possible please