I have this issue, 2x 1440p monitors (1x 144hz 1x 165hz), the only thing I haven't tried yet is the mini display port. Edit:- Ok so using the DP cable has worked and my monitor is actually using the 4060 at its highest refresh rate. its quite likely that the issue is that the HDMI cables are just old ones that cap out at 60hz. to get multiple monitors you'll need a DP Hub so you can plug multiple DP cables in and then plug the hub into the laptop via the mini dp port. I did have this monitor connected via the thunderbolt port yesterday, with a multi adapter (1 HDMI port several usb ports) connected via the USB-C (thunderbolt) port on the back of the laptop but it capped out at 72hz. that could either be the HDMI cable itself, or it was the limit with connecting via that port/adapter. for me I don't really mind one screen running at 60hz so I won't bother buying a DP hub. seeing as I can get one of them to run at its max refresh rate, I don't game across two monitors one of them is just a spare browsing screen anyway. but I would check to see if your HDMI cables are old and or try a male to male (mini) dp cable.
... Afficher plus