- download the last legacy driver available 16.2.1 beta
- then install the patcher AMD/ATI Pixel Clock Patcher maybe fix your problem and they still working on it, maybe you can try some support there too.
The Custom Resolution Utility(CRU) is for if you want to reach 4k resolutions.
Finally i found how enable crossfire via regedit.... put Find Crossfire, all settings are "0" just change ALL to "1", now search ULPS, the are "1" change to "0" all you can find.. restart! and crossfire always be enable..