In my rig, I have 3 7970's and in the past I have been able to trifire them with no issue. For reference, this system is about a year old.
However, lately CCC has not allowed me to enable 3-way crossfire, as demonstrated by the below screenshot:
In the Device Manager all 3 cards seem to show up just fine and in CPU-Z.
I was running the latest 13.11 Beta drivers but decided that may be the issue and uninstalled those using AMD's tool via the Add/Remove Program feature in Windows 8. Then I installed the latest 13.2 drivers and CCC all over again.
The thing that gets me is that these cards use to tri-fire just fine, I'm not sure what happened or when it happened.
One odd thing about this machine however, is that when I turn lights off in my apartment (for instance turning the pantry light on, waiting a couple of minutes and then turning it back off) Windows makes a noise as if I have just disconnected a device. I have since connected an APC Battery Backup to help deal with any odd power issues.
Does anyone have any suggestions for next steps? I'm thinking of running each card in each slot by itself (no other cards in the machine) just to prove that each card and each slot works in every combination. However, I'm hoping that will prove to be a futile exercise because it seems like AMD's drivers can get kind of weird for some people with these types of setups.
Any help you guys could provide would be extremely appreciated!