ASUS GTX680 DIRECTCU II TOP SLI HELP

I just started my build and wanted some help on the placement of the 2 GTX680's

Coolermaster HAF X
Phanteks CPU Cooler
Asus P8z77-v deluxe


These are triple slot cards and I am wondering where is the best place to put them. I am thinking it has to be the first two x16 slots which
puts them pretty close to each other.

My main concern is the cooling if these two cards are so close together.

I dont think I have the option of using the last PCI x16 slot .

I do have the 200mm side fan and a couple options for cooling with a 120 fan VGA duct and the 80mm vga holder.

Would love to hear from someone that has a similar setup. Or anyone with advice/suggestions.

As this is my first build, I am being overly careful no doubt but can't help it.