I have a QN55Q6FNAFXZA QLED TV and it makes popping noises every few minutes. This is the second QN55Q6FNAFXZA TV I have purchased in 30 days. I took the first back because it was making the same popping noises.
The TV makes the noise no matter what I do. For instance the noise occurs if:
the volume is muted
the volume is low
the volume high
audio out is selected
The TV will make the noise if no inputs are connected to the TV.
After I watched the TV for a period of time and turned the TV off, the TV made the popping noise while off.
After using the TV and powering off, it will even make the noise if you unplug the power cord from the wall. Under the worst case, the TV made the noise once every 10 or 15 minutes for 2 hours.
I sent a private message to Samsung today. Hopefully this is a known and fixable problem.
I guess there is always the possiblity that the noise is thermal expansion, but it certainly doesn't sound like it to me.
Definitely does it on HDMI2 which is Directv. It also does it after the TV us turned off and even unplugged, up to an hour or so after turning it off, sometimes every minute, sometimes with several minutes in between the pop/click sounds. The noise is definitely NOT coming through the speakers. It sounds like when something new is heating up or cooling down and you get that clicking/popping sound.