Tried SMOS for the first time with three brand new Sapphire 279x cards. I used the config that's on the SMOS site. Consistently for the last day or so I have one card failing on me after any where from an hour to a few hours into mining. It's hash rate slows then it dies. The other two cards are hashing well around 470-480kh/s with few problems. I thought it might be a power problem so I hooked up one card to a separate PSU (one card on a 650 and the other two on an 860). That didn't seem to help. I do a coldreboot and sometimes it reboots no issues other times it reboots and gpumon or cgminer just don't work. I've double, tripple, quadruple checked the connectors, the power cables, ect. Not sure what other problem solving steps with this I should take. The cards do seem to work when the systems finds them and mining actually starts.

My only other experience with mining is another rig I set up with BAMT running two 7950s. I think I got spoiled there because it was SOOO easy to setup and has given me almost no problems and I'm hashing about 650kh/s per card on average. These 270s on SMOS have been nothing but headaches. Anyone having similar issues with 270x's?

Specs:
Asus M5A99X EVO mobo
Samperon 145
4gb ram
3  x apphire DUAL-X AMD Radeon R9 270X OC 2GB GDDR5
650w evga & 860w seasonic
mobo has 5 pci-e slots (three 16s, two 1s) and i'm using slot 1 (16) with riser, slot 3 (1) with riser and slot 5 (16) no riser
interesting slot 2 which is a 1 slot is not recognized by the OS at all, tried plugging into this one and the card didn't show up at all when i logged in

Any ideas? Anyone... Beuler??