Hi,
being new to the community, I've been searching all over the place for the problem I'm experiencing on my new T420s laptop (i7 CPU, HD graphics + discrete Nvidia 4200M).
I'm connecting my HDTV (1080p screen) to my laptop using the Displayport output (using an adapter cable to HDMI). Looking to extend my desktop across both screens (default was cloning), I saw in my Intel HD graphics control panel that I was in single display mode.
In the Nvidia control panel, I see the external monitor, so it must be using the Nvidia card for the 1080p output. The PhysX panel indicated indeed that my HDTV is on the NVS 4200M card.
So far so good, extending desktop is no problem. I leave other parameters unchanged.
Now, starting up a full 1080p movie using VLC media player on the HDTV is giving me a rather choppy video. Using the debug messaging feature of VLC, I see that some frames are being skipped.
The NVidia control panel has the option to dedicate a specific program to be used with your choice of graphics. I added VLC to this list and selected now the integrated graphics instead of the autochoice (which would be Nvidia). Playing back that movie has no issues at all, perfectly smooth.
So what's going on here? The more powerfull Nvidia chip is giving me a rather crappy performance on video?
Forum posts at VLC would suggest an upgrade of video driver.
My laptop has the latest Lenovo approved drivers (Intel HD: 8.15.10.2321 and Nvidia: 8.17.12.6871 which is actually 268.71 if I look in the Nvidia control panel), while NVidia lists a more up to date driver (280.26). I haven't installed the Nvidia drivers yet...
Note that I don't see that choppy video when I'm not running full screen, but downsizing the window of VLC a bit.
