4k @60Hz monitor refresh rate inconsistencies?

[thisisjolley]

Hi all,

I just purchased an LG 27UD58-B (an older monitor that I found for pretty cheap) and I'm pushing 4k @60Hz through my Lenovo Yoga 920-13IKB. No dedicated GPU on this laptop, only Intel UHD 620 integrated.

To the point though, I'm getting a very weird refresh rate issue...I noticed while watching an LTT video that it seems to get slightly choppy in waves, so I ran a few tests and found that my refresh rate is dipping to 48Hz and then going back to 60Hz every 2-3 seconds, and repeating that wave pretty consistently. I've never run into anything like this before. My first thought is that it must be the HDMI adapter I'm using (BlackWeb USB-C to HDMI, rated for up to 4k @60Hz) but before I went out to buy another one I'm curious if anyone else has run into an issue similar to this with different results.

 

My UHD 620 drivers are up-to-date, and so are any other drivers that might affect this...do I need to go and buy a new adapter? Was buying one that was only $20 a mistake? Thanks in advance!