I recently expanded my Windows 11 setup from three displays to four. The current setup includes two Dell P2219H monitors at 1080p and 60Hz, a Gigabyte G27Q at 1440p and 144Hz, and a Hisense U7SG TV running at 4K and 165Hz. The monitors are connected through HDMI and DisplayPort, while the TV uses an Ultra High Speed HDMI 2.1 cable. My graphics card is a Gigabyte 8GB RTX 3070 Eagle.
Any combination of three displays works normally, but I can only use all four when I change the TV's HDMI format from Enhanced Pro to another mode. Enhanced Pro appears to be required for 4K at 165Hz. I've also tried rearranging which displays use HDMI and DisplayPort, but I still can't keep all four active while the TV is set to 4K 165Hz. Is this likely a total bandwidth or GPU output limitation, and is there a way to verify the limitation before replacing hardware?
1 Answer
This sounds most like a total display-bandwidth limitation rather than a bad cable. Driving a 4K display at 165Hz consumes a huge amount of GPU link bandwidth, leaving less flexibility for the other three active displays. That’s why three displays work in any combination, while the fourth fails only when the TV uses its highest-bandwidth HDMI mode.
The limitation can usually be checked in the RTX 3070’s specifications and NVIDIA’s display-configuration documentation. Look for the maximum number of simultaneous displays, the supported HDMI and DisplayPort versions, and the maximum resolution and refresh combinations. The GPU may support four displays in general without supporting this exact four-display workload at the same time.
That makes sense. I was hoping the HDMI 2.1 cable would solve it, but it sounds like the cable can only provide the connection the GPU and TV are capable of using—it can’t increase the GPU’s total output bandwidth.