This is an old and new issue.
Have an XDCam-HD preset Sequence. XDcam footage is green screen, layer below is a white background. Layer above keyed footage is an imported PSD with 2 logos on same layer with transparancy.
Sequence settings: MRQ and MRB are checked, and composite in linear color is unchecked.
Playback resolution and Paused resolution both set to full.
Using Cuda acceleration in project settings, and all hardware accelerated FX, program plays back perfectly and looks excellent.
Problem: While Cuda acceleration is enabled, when the playhead is paused, or stopped, logos look terrible. The alpha looks like it has noise in it. However, when you hit play, everything looks good.
Supers created in the Titler are not affected and look fine.
If you render the seqence for preview, logos render with terrible result, as if paused. Also, on export you get the same bad looking logos.
If you disable hardware acceleration, all is well.