Surprisingly it was a Display setting. Deep Colour Output. Turned it off, and hasn't flickered in a week!
No idea why it only happens with Optical in though.
Type: Posts; User: Sicarius123
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Just to make sure, I isolated the PS3 to one side of the TV so no other nearby cables can interfere and tried 3 HDMI cables, all of which work with no issue on the Xbox and my Bluray player.
I remember having this same problem years ago when I first got my home theatre system, and after weeks of stuffing around with settings I managed to fix it.
Fast forward to today and my PS3 phat...
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