I recommend you try these steps first:
1.Disable Compiz and use your system for a while; by doing so, you should prevent PowerMizer from having to switch the power supply by ensuring the load on your GFX card never passes a certain level. If it’s still flickering, something else is the culprit.
2.Run Compiz with the –loose-binding option but not with –indirect-rendering. If you’re using fusion-icon, which I heavily recommend, you can right-click it and toggle these under “Compiz Options”. If you’re manually starting it, you’ll need to add/remove these switches to whatever process you use to start it.
3.Open CompizConfig Settings Manager, and in the Workarounds settings, under Utility, enable Force Synchronization between X and GLX.
4.If steps 2 or 3 worked, play around with those three settings until you find something that works for you. I personally enable loose binding due to the performance increase it gives me, but your mileage may vary.
It may help you