I hope someone can help me out here.

While holding down control and using the scroll ball to zoom in and out I've noticed that I get screen tearing.

Things I've tried.

* Clean install of lion.

* Apple hardware test ( the results said that there were no problems at all)

* Smc reset

Below are my specs and my HD youtube video that showcases the tearing.

Also.....In the video the fan noise is not my iMac its just my bedroom fan.

iMac screen tearing - YouTube