I have the above TV and have had it for just over a year so I am now out of warranty (incredibly annoying) it has started making an incredibly loud squealing noise that is coming from the TV itself and not the speakers. The only way to get this to stop is to reduce the backlight on the TV to 1 in the picture settings and then it's almost non-existent. It has also recently started to do a boot loop, turns off, then back on, displays the piture (no squealing) for a few seconds then turns off again. I've tried everything Samsung suggests with no success.
I am convinced that there is nothing wrong with the TV and suspect the one connect box might have something to play with it.