Frame micro-stuttering has been one of the longest running problems in high-end multi-GPU setups, although at times the reports of the issues have been overblown or dismissed. NVIDIA implemented driver-level fixes to address a large portion of it some time ago, but reports has been sharply critical of AMD HD7000-series CrossFire configuration's susceptibility.
News coming out of twitter yesterday makes it sound like a solution could finally be coming for long-suffering users. The official AMD Radeon Graphics account announced 'good news for CrossFire users'. stating that a driver-level fix to frame pacing would be available on July 31st:
The trouble is, this may be too late for AMD. Those running a high-end multi-GPU solution would be amongst the biggest spenders in the enthusiast market, and certainly some of AMD's most loyal supporters if they buy early in the life-cycle. To have gone this long without a fix, and to have the Red Team even cast doubt on whether it was a problem in the first place, can't have endeared them to those who have forked out £500+ on dual-GPU solutions including the flagship HD7990.
Hopefully the fix will be an end to the issue.
Sources: ComputerBase.de, @AMDRadeon