Try it with only one card in first, see if you can get it running and add the other later.
FYI, you only need one x-fire connector but I use two as it doesn't hurt.
I've already bought a P67 Deluxe and have an SSD drive so no I won't be upgrading.
I'm just hoping that Asus don't dump supporting us early adopters now they've brought out the Z68 versions.
+1 for that... with a load of paper towels laid out just in case.
You get pretty good at it pretty quickly and once you get it sorted properly you'll only have to drain it when you upgrade.
Sounds more like the fabled "cold bug" to me!
One of my Asus cards does this if I have it as primary.... goes away if the card warms up which isn't so easy on H2O.
Fortunately the other card is fine with 2D at low temps.