I'm have the rampage IV and 3 asus Titan's in SLI.
My monitor (Sharp pn-k321 - 32" 4k monitor) uses Display MST (multi stream transport).
If I turn this option on it works fine, rebooting is also fine. But a cold boot POST will not work. I have to power up a few time and get into normal/safe mode boot/bios to get it up again.
(to get 60hz at 4k - I need MST)
My guess is it needs a bios updated to address this. I have yet to try 4004 - which i'll do tomorrow, but I don't see release notes talking about MST.
full system specs:
Asus Rampage IV Extreme, i7-3630k (6 cores) 4.7ghz (water cooled)
Mushkin RedLine ram 1866 DDR3 (32gigs Quad channel), Seasonic 1250 Watt PSU
OCZ 128 Vector SSD (system drive), OCZ 512 Vector SSD x2 (raid 0), Seagate 3TB HD
Nvidia Titan 3 way SLI (watercooled), 32" Sharp UltraHD pn-k321 (3840x2160)
Logitech G19 / G9, wired 360 controller
audio: Audiolab M-DAC -> Rega Brio-R (AMP) -> Denon AH-D5000 (headphones) or PSB imagine mini (speakers)