In Adobe Photoshop CS5 Extended (perhaps in earlier editions too), under 'Edit > Prefs > Performance > GPU Settings (Advanced Settings)' you can choose the level at which Photoshop will utilise your gfx card: Basic, Normal or Advanced.
Default is 'Basic', and there comes a warning with 'Normal' or 'Advanced' stating that it 'may cause visual defects on some GPUs'.
What constitutes a visual defect? Does it mean on-screen rendering whilst these settings are in use, or something which might permanently damage my GPU?
Thanks
