LG 27UP550N Owner's Manual page 32

HDMI Timing (Video)
Factory support mode
(Preset Mode)
480p
720p
1080p
2160p
32
Horizontal
Vertical Frequency(Hz)
Frequency(kHz)
31.5 60
45.0 60
67.5 60
135 60
Remarks
When HDMI ULTRA HD Deep Color is set to ON