Screen flicker started after supplemental update to 10.8 5 on my 2012 mac mini

The problem monitor was one of 2 Dell S2740L and is connected via a mini DP to HDMI cable

The 10.8.5 supplemental update came with the iTunes 11.1.1 update

The screen would soften and flicker every few seconds and sometimes black out

Tried lots of fixes including another cable but nothing worked

Restoring back to previous know good version has solved the problem

Looks like fixing someones flicker problem has started another