Look under the crossfire tab in CCC. Uncheck "Enable crossfire".
Check "Enable " when you want it again.
Or right click the CCC icon in the task bar,move cursor over the first entry of your cards. Select "disable crossfire".
Thats about it.
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MSI 970A-G46/Athlon 260@3.5ghz/2x4870/TX750M/4gigDDR3