Need advice for gtx 680 and gtx 650

To answer your question no that motherboard does not support quad sli you would only be able to add two cards 2 x 680 in sli The ASUS SABERTOOTH Z77 comes with two PCI Express 3.0/2.0 x16 slots, one PCI Express 2.0 x16 slot, and three PCI Express 2.0 x1 slots.

The two PCI Express 3.0/2.0 x16 slots are controlled by the CPU, with the first slot working at x16 when only one video card is installed, and with both working at x8 when two video cards are installed. Since these slots are controlled by the CPU, they will offer PCI Express 2.0 bandwidth (8 GB/s at x16) when a “Sandy Bridge” CPU is installed, but PCI Express 3.0 bandwidth (16 GB/s at x16) when an “Ivy Bridge” CPU is used.

The third PCI Express x16 slot is 2.0 and always works at x4 speed. If you want to install a dual-slot video card in this slot, you will need a computer case with at least eight expansion slots. (Computer cases usually have seven.)

The PCI Express x16 slots support both SLI and CrossFireX technologies.and no you can't sli a 680 with a 650 you can use a 650 as a dedicated PhysX card though..Card i recommend links:
670's:
http://us.ncix.com/products/?sku=71107&vpn=GV-N670OC-2G...

http://us.ncix.com/products/?sku=72914&vpn=N670%20PE%20...

http://us.ncix.com/products/?sku=71741&vpn=GTX670-DC2T-...

GTX680 ASUS TOP:
http://us.ncix.com/products/?sku=71119&vpn=GTX680-DC2T-...
TMSI's GTX 670 Power Edition uses the famous Twin Frozr IV cooler from the MSI Lightning and comes with a large clock speed boost out of the box, making its default clock speed even higher than GTX 680 stock clocks. MSI is asking a $30 price premium for their card, which doesn't look unreasonable, given the improved cooling and higher clocks.
hen we have Gigabyte, who are known across the world for their patented Windforce cooler with triple fan design, which looks very similar to the solutions we see from leading GPU cooler; Arctic.

The card comes with a factory overclock straight out of the box to give the user even more power than a reference GTX 670, which is already a powerful card for a reasonable price. Having an overclock means the reference clocks have been pushed further, past their stock limits, meaning that the extra cooling provided by the Windforce 3X cooler should really come in handy.Asus GeForce GTX 680 DirectCU II TOP

Here we have the big-boy of the group, Asus’ GeForce GTX 680 DirectCU II TOP. The Asus GeForce GTX 680 DirectCU II TOP is a custom card through and through. It features a unique PCB design, with a beefed up digital / programmable VRM, and a massive triple-slot / dual-fan cooling solution equipped with a dust-proof fan design. The fans used in the cooler have additional ridges in the bearing design, which prevent dust from entering.

The custom VRM on the Asus GeForce GTX 680 DirectCU II TOP is designed to provide more stable power than reference solutions under load and the card also sports Asus' VGA Hotwire feature. VGA Hotwire works with Asus' Extreme Series motherboards and allows for voltage control through the motherboard's UEFI. The Asus GeForce GTX 680 Direct CU II also features Asus’ “Super Alloy Power” technology. According to Asus, the Super Alloy components on the card are reinforced with special alloy formula and manufactured under high temperature and pressure to provide more stable power and noise-free operation. The super allow caps on the card will reportedly last much longer than standard capacitors too.

The large cooler on the card, which has multiple copper heat-pipes and myriad aluminum fins, is designed to more efficiently and more quietly cool the card’s GPU and memory. The result is a gigantic, triple-slot GeForce GTX 680 that’s clocked higher than any other tested, but is also relatively quiet and cooling, and quiet overclockable.