5k monitor (lg 34wk95u) reverts to 3440 x 1440 res when 16 inch macbook pro goes to sleep.

I finally figured this out by loading SwitchRezX, from https://www.madrau.com/srx_download/download.html, once I loaded this rebooted everything just started working correctly. I now have the ability to fully run all resolutions on the LG 34wk95u and have also added a second 4k lg monitor in portrait mode that is working flawlessly as well.

I had to run SwitchRezX once. Then I didn't need it again... don't know why... just that it worked for me. I get full resolution at 5k2k with a active 1m thurderbolt cable from Caldigit.

Thunderbolt 3 active charging cable from caldigit for the 34 dell 5k2k and the Monitor cable that came with the 4K second monitor worked as well. Make sure you plug the 5k2k by itself on one side of the MacBook.

Using a new thunderbolt 3 cable could fix everything! Make sure the cable supports 40GB/s. The cable in LG monitor box is just 20GB/s.

Thanks for the suggestion! The SwitchRezX worked! And I change another Thunderbolt 3 cable makes everything perfect. 40GB/s cable!

On my MBP 2019 16-inch I get a different experience with my 34wk95u with a thunderbolt 3 cable plugged in. I get the resolution I expect, but the screen is not filling the entire screen. It appears shrunk down and doesn't fill the whole screen. My MBP 2017 15-inch it works 100% perfect. I expect this is a driver issue for the 5500m.

I also tested using a display port and full 5k resolution, but only at 30hz.... and I am getting only 4k and 3440x1440 as options. Again this feels like a driver issue with the video card.

My MBP 16" can't get the 5120*2160, I just have 3840*2160 and 3440*1440 with the thunderbolt 3 cable in the LG box... Is there anyone to fix the problem? It is 10.15.2 now, still have it, so sad

I was planning to purchase the MBP16 tomorrow to use it with external screen with 5120x1440 ... i thought it should work.

what adapters are you using? As long as i know the apple adapters do not support higher than 3840x1080

Do you get full resolution with 16" MBP and high speed Thunderbolt cable? Or you you have to run SwitchRezX? Any other issues?