Try disabling CPU core parking as some users reported that it solves such flicker issues:
http://bitsum.com/about_cpu_core_parking.php
http://www.coderbag.com/Programming-C/Disable-CPU-Core-Parking-Utility
http://bitsum.com/about_cpu_core_parking.php
http://www.coderbag.com/Programming-C/Disable-CPU-Core-Parking-Utility
