I built, and have used the following system for the last 6 months:
Asus Maximus IV extreme Z
Kingston HyperX 8GB (4 x 2) 1600
Asus Matrix GTX 580
Kingston HyperX 120GB SSD
Western Digital 1TB Caviar Black
Thermaltake 850W Toughpower Grand
Thermaltake Level 10 GT
Windows 7 64 Home "Premium"
Razer Blackwidow Ultimate
and a cheap acer 23"
Okay my question is that I want to upgrade my graphics card to two 680 GTX. I want also to add a soundcard, either a Asus Phoebus, or Xonar. I want to put the soundcard in the topmost PCI-E X16 slot, as I understand that this will allow my two graphics cards in the other PCI-E X16 slots to run at X16, X16. I aslo would like to use the Asus GTX 680's BUT they use an obnoxious 3 slot cooler. Will these cards fit? My second choice (distant) would be the MSI twin frozer, or a Gigabyte GV-N680OC-2GD. I appreciate any help! Also I would be fine if the second Asus card was not able to use both vents and overhung on the bottom of the motherboard, as long as it fit.
On this board there are 4 PCI-E x16 lanes, they will work as X16, X8-X8, or X8-X16-X16. I would use the soundcard in the 1st X16 slot, ignore the X1 slot, put the 2 slot 680 in the second X16 slot which would cover the third X16 slot, and the second 2 slot card in the fourth X16 slot which would cover the bottom most X1 slot. Upon closer inspection there seems no way to use the Asus cards. Big bummer. It is strange that Asus's Upper tier "ROG" board would not support 2 of their top graphics cards and a sound card.
So you believe that I will be able to stuff two Asus GTX 680's and the soundcard in the configuration you specified? Will I have any performance issues regarding the X16-X8 PCI-E connections on the graphics cards? Was I mislead about using a soundcard to achieve the X16, X16 speeds on the graphics cards or have i misunderstood something?