Lip sync problems after upgrade to 4K monitor

[redlester]

I'm on a "Trash Can" Late 2013 Mac Pro, 3.5GHz 6-core Xeon with 32GB RAM. OS is maxed for this machine at Monterey version 12.7.1.

Until recently I was using it with an old (roughly 2008 model) HP 24" monitor, which I think was 1920x1200 resolution.

I've recently upgraded to an HP U28 4K monitor, which I have to say is wonderful quality. For practical visual purposes am using it scaled at 2560x1440 but the problem described below is still present regardless of scaling setting.

I'm using an HDMI cable, although this monitor has USB-C and DisplayPort connections. The Mac Pro has an HDMI 1.4 output.

Since making the switch I'm suffering niggling lip sync issues, and it doesn't seem to matter what the source of the video is. Sometimes, not all the time, YouTube videos are way out of sync. Often they are fine. On YouTube am normally viewing 1080p material most of the time, but the problem seems irrespective of what viewing quality is. I also get the problem, in fact it tends to be worse, on playing mp4 videos via Quicktime from my local storage drives. Particularly from my Synology NAS drive, I realise there could be bottleneck issues with this but my computer is wired directly into my router via LAN cable, am not using WiFi. Again this is not on every video, just certain ones, but ones which am almost certain played in sync on the previous monitor.

These issues have only appeared since the new monitor arrived.

What are my options? Is it finally time to upgrade to a Mac Studio or Mini with a modern processor? Could it be as simple as trying a DisplayPort cable (I would need to buy one).

 

[PaulD-UK]

HDMI 1.4 can only support 4096×2160 at 24 Hz, 3840×2160 at 24, 25, and 30 Hz, and 1920×1080 at 120 Hz.
So to get useable 4K/60 you must try a miniDP to DP1.4 cable.

But because the 2013 MP is DP1.2 only, its designed to do 5K over two Thunderbolt 2 cables.
Each miniDP port supports at least one half of 5K, but 4K/60 is probably possible through a single cable.

 

[DeltaMac]

As a test, try using in default/native resolution. (You will probably find that your syncing issues will mostly vanish. Scaling can often pull your video performance down significantly. It's something you may have to consider when deciding what resolution to use.
You said you are on macOS 12.7.1 ~ Latest Monterey is 12.7.6, probably the last release update for Monterey.

 

[redlester]

You said you are on macOS 12.7.1 ~ Latest Monterey is 12.7.6, probably the last release update for Monterey.

Thank you, you're quite right. For some reason it hadn't prompted me to install so I will do that manually.

 

[redlester]

HDMI 1.4 can only support 4096×2160 at 24 Hz, 3840×2160 at 24, 25, and 30 Hz, and 1920×1080 at 120 Hz.
So to get useable 4K/60 you must try a miniDP to DP1.4 cable.

But because the 2013 MP is DP1.2 only, its designed to do 5K over two Thunderbolt 2 cables.
Each miniDP port supports at least one half of 5K, but 4K/60 is probably possible through a single cable.

Thanks. Sounds like a DP cable might be worth a try.

 

[redlester]

For future readers of this thread...

I purchased a Mini DisplayPort to DisplayPort 1.4 cable, and this has made a noticeable difference to the specific video that prompted my original post. The lip sync is still out, presumably due to the issues mentioned by @PaulD-UK above, but by a fair bit less than it was on HDMI and is now just about bearable to watch. I haven't noticed any issues at all on YouTube videos since the change in cable. This will do me until I upgrade eventually to a more modern Mac, when I then should be able to use USB-C.