Second Display Issues 4k/hdmi

Hi there,

I currently have a Samsung S23B350 as my main monitor running at 1080/60 via hdmi.
I also have a 4k TV (Toshiba 43U6763DB) connected via D-Sub, running at 1080/60. In this configuration everything works great, there is slight input lag on the TV (TV specs says 38ms, and this is what I feel like I'm getting) but I can deal with this ok.

I'd like to run the TV at 4k (naturally), but when I swap the cables around so that the monitor uses the D-SUB and the TV uses hdmi I get some bad issues.

When I play videos either locally with VLC/WMP or streaming from youtube the videos play perfectly on the main monitor, but when I drag it over to the TV it goes out of sync. I'm talking at least half a second, much more than the input lag i get when just navigating the screen with the mouse. So I tried just running the TV display on its own, and it seemed to fix the sync issue, but then the colors are all messed up (Green and magenta horizontal bands). So I switch back to 2 displays and the colors are fixed but the sync is gone again. I try this all again and this time the colors are messed up no matter what i do.
So I plug the PC into a second hdmi socket on the TV and I basically start at square one again. Except this time in my attempt to fix the sync issues I notice in Display settings that the TV's resolution is set wrong (1 slider position too low) so I set it to 3840*2160 and the colors become messed up. I gave up after that and I'm now back to using the D-Sub for the TV.

I'm using;

Windows 10 Pro
Phenom 955 (3.2)
8g ram
Gigabyte GTX 950

CPU and GPU usage is fairly low when playing 4k (10% and 20% respectively) It's a clean install of W10 and latest display drivers (391.01)
Both the GPU and TV support HDMI 2.0

My TV plays 4k perfectly via its built-in Youtube app, also no issues with using a Tivo box via hdmi.

I have googled a lot and I see people with the same issues, but none seem to be resolved.

Any ideas guys?

Thanks

 

I'd check either the Gigabyte or NVIDIA download pages to be sure your video drivers are up to date. This may solve the issue - let us know if it does or does not.