Question Vizio P-Series 55" only refreshing at 30 Hz

airickm3

Honorable
Apr 24, 2016
2
0
10,510
I have an entry level 2017 iMac Pro running Mojave 10.14.6 which is connected to
an Apple USB-C to HDMI adapter, which is connected to
an AmazonBasics 15ft Premium HDMI cable (18Gbps) which is connected to
a 2018 Vizio P-Series 55" screen

Despite the fact that each link in that chain supports 4k at 60Hz, when I check the system information on the iMac Pro, it shows that I'm only displaying at 30Hz:
ab86bd93-1ef5-4539-87d9-7c608c11f623


How can I get the full 60 Hz refresh? What am I missing?
 

airickm3

Honorable
Apr 24, 2016
2
0
10,510
The iMac Pro is capable of outputting 4k at 60Hz from the USB-C ports (which is where I’m plugged in) and yes this particular port on the Vizio can take 4k 60 Hz.
I just found the solution the other day - Mac OS Display settings don’t actually show all possible resolutions, but I downloaded EasyRes and then was able to select 4K 60Hz. So it wasn’t the hardware at all, just a software issue.