There are many factors I have yet to explore so
So, this problem has three parts that add up to one major problem.
Here I stand with a puzzle that has me going in circles. With 2 7990's (=quadfire) Eyefinity craps out by connectiong and disconnecting. This has all pointed to Mini Displayport to DVI connector (or a similar) required in order to use eyefinity. This as an example.
Problem 1: The adapters are crap. Poor manufacturing or unintentional use makes these adapters good for a few months if at all. Many recorded instances on shopping sites narrate this, regaurdless if they are AMD recommended components. Even when a new adapter is obtained, and all is good and well crossfire included, it flakes out eventually, which leads too the following.
Problem 2: Crossfire is frying your active adapter. This is purelly speculation but I believe Crossfire somehow puts too much strain on the adapter causing it to crap out and eventually fry all togeather. That does'nt make much sense to me but it might be a possibility.
Problem 3:The adapter is fine as long as you use one GPU. The adater may work just fine but it will flake out with Crossfire used in conjunction. This may or may not be related to the the PCIe itself, due to the fact that a single 7990 utilizing internal crossfire works just fine as far as I can tell.
Had this problem with 5870s trifire
System is substatially over clocked but have the same problem on normal clocks.
Rampage 3 extreme
Core i7 980x
1x 1200 and 1x 750 powersupply
(forgive my spelling and grammar as I suck at it and don't care)
For now its either / or.
Either use crossfire on a single display or eyefninty with one GPU.