It's been a couple of years since I checked this thread, which fortunately means that I have had no issues with my UN46C8000. I've been extremely pleased with the performance and pic quality of this set, being used in my master bedroom for the last 4 years and 4 months. That is up until Sunday night when I tried to turn it on to watch the Cable box and received a "no signal check connected devices power cable connection and source selection"...almost exactly 4 months after my extended warranty ended!! I switched on the dune media player and switched source to HDMI 2 and nothing, tested all the other HDMI slots, and no luck. I unplugged the HDMI, unplugged the TV power cable, waited a couple of hours and plugged everythign back in the "no signal check connected devices power cable connection and source selection" message popped up again. After doing some research, it seemed that it either needed a factory reset, or to switch out the main board. Fortunately, resetting the TV worked, and it is back to working flawlessly again. In case anyone runs into this issue, before wasting too much time, try unplugging everything for a few minutes and reconnect to test if it's an HDMI handshake issue. If that fails, simply press and hold the "ENTER" button on the remote while the TV is powered on to reset.