Windows – Persistant lag during video playback on a high end HTPC

video-playbackwindows 10

I have high end PC but I cannot playback videos smoothly. I have a Intel Core i7 8700K, 16gb RAM and GeForce GTX 1080. I have my PC connected via DisplayPort to HDMI cable to a LG 75UM7110 TV. I must use this cable since that is the only port working in this old GPU. The TV has been set up for maximum speed for PC usage. I used this machine fine for a long time with perfectly smooth playback, even 8k was smooth most of the time. What has changed recently is the TV and a fresh Windows 10 build install (and MPC-HC version update).

For software player my choice is MPC-HC, and will not entertain ideas for alternate players. The player is set to use hardware acceleration (displays Playing [H/W] when playing, indicating successful DXVA acceleration). I playback videos off HDD (3500mb/s SSD also tested). The videos are smooth for some seconds, then lag a little, repeat. There does not seem to be any difference between resolution, high or low bitrates or old/new codecs (from XviD to x265). None run smoothly, but it is difficult to tell if the amount of lag differs. The lag does not extend to playing games. During 4k x265 playback and a whole punch of idle-ish programs my CPU stays within 6-8% (with MPC-HC using 31-33% of that), my HDD at 0-2%, and GPU at 12%. MPC-HC memory usage is steady at 326-328mb.


A friend of mine reproduced the problem with his laptop connected to my LG TV with his own cable, into a different HDMI port. The problem does not appear in his laptop screen, only the duplicate output to the TV. These are some of my TV settings:

  • Picture Mode: Game
  • Sharpness: 0
  • Dynamic Contrast: Off
  • Super Resolution: Off
  • Eye Comfort Mode: Off
  • Energy Saving: Off
  • HDMI Ultra HD Deep Color: Off
  • AI Recommendation: Off

Best Answer

  • Interesting well described question: since only two things have changed, if it's conveniently possible to return to the preUpdated OS configuration, if the situation persists, that would imply something re the new tv; if the previous tv could be put back in, that would imply something with the tv+OS, and if the situation occurs with the updated OS with the previous tv, that would imply the update; maybe try check with the tv manufacturer re possible aspects/ fixes: the manufacturer may be unaware of the situation, especially if associated with the new OS update, and there could be other things that may have been updated in the background, depending on updating aspects, which could mean that something has been changed without the change having been indicated, depending on updating aspects, and so there could be more than two things which have changed: implying tv & OS are both ok. There may be something(s) operating in the background which are causing lag. Cable length & connectors could be a factor, but if it was functioning well previously those may be ok. Try adjusting only one item at a time, then two items at a time etc to isolate the specific set of conditions which is/ are the cause. And maybe redo all settings to be certain they're set where intended. (Excellent, nice that that worked; sometimes toggles may indicate values, yet the actual values may differ: sometimes resetting/ switching them off and backing out & then reentering and setting them to the intended value again sets them to where they're intended!)

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