I finally upgraded to FC16 a few days ago, and then updated packages a couple of days later. Since then the brightness on the HDMI display flickers between high and low,making it unviewable.
- GPU is GeForce 8400 GS (G86)
- Nouveau version is 1:0.0.16-27.20110720gitb806e3f.fc16
- Kernel is 3.3.1-5.fc16.x86_64
Output to a VGA LCD is fine, both as single output or running along with the HDMI using XRandR. The HDMI display is a Sony Bravia TV which has worked and still works fine in all other respects - the display is fine using the VGA input at the same resolution and refresh rate as HDMI, so nothing physically wrong with the TV. To be clear, this problem didn't manifest immediately after the FC16 upgrade, but only after the subsequent package update.
Thanks for any suggestions,