Just bought a VIZIO XVT3D474SV, and I'm noticing 120hz in some sources and channels, but not others, wondering what accounts for that.
For example, if I watch a DVD on the XBOX 360 via HDMI, then it definitely upconverts to 120hz. If I watch the same DVD from my PC via HDMI, then it seems to stay at 60 hz (or less).
I assume the Vizio is upconverting the XBOX signal, I know the old DVDs aren't 120hz natively, and I don't think the 360 can even put out 120 hz. My GPU only puts out 60 hz, but if the TV is doubling and smoothing the XBOX framerate, why not the PC?
perhaps not all hdmi inputs are linked to 120hz mode.
This appears to be the most likely issue... it seems the side HDMI ports don't do upconversion. I can't find this documented anywhere though, so I'm not sure if it's hardware design, software dropping those ports to a gaming mode, or my system has a defect.
It's also kind of hard to clearly test whether something's in 120 hz or not. I can sorta tell most of the time, but it's not very objective. So another possibility is that this is all in my mind.
120hz televisions can only receive a 60hz signal. the tv doubles the framerates.
From the research I have done, I think this is most likely the problem. I was deciding between 60hz and 120hz and read that 120hz TVs only accept 60hz signals from PCs. So your TV is recognizing the signal as 60hz and then doubling the frames. Here is another thread dealing with the same issue: