SOurce : ftp://download.nvidia.com/Windows/7...lease_Notes.pdf
NVIDIA 77.72 的 Release Note 有說明此問題.
GeForce 6800/6800GT/6800 Ultra, GeForce FX 5700/5600 :
NVIDIA Overlay gamma controls under Standard
mode do not work properly, resulting in overly dark or overly bright
video.
To work around this issue:
1 From the NVIDIA control panel, click the Color Correction menu tree
item.
2 From the Color Correction page, click the Apply color changes to list
arrow and select All, then click Restore Defaults.
3 Click Apply.