I'm connecting my laptop to a 4K display via HDMI. Some of the time, it works fine, but other times, the graphics card/driver defaults to sending 1080p to the monitor, and doesn't display the options for higher resolutions. Does anyone know why this would happen or how to fix it? (Relevant system and monitor specs are included at the end of this message.)
As I said, sometimes it works fine, but sometimes I'll plug the monitor in and the graphics card will only send 1080p. When the issue is occurring and I look at the Intel HD Graphics Control Panel, I can see that the driver still knows the maximum resolution of the monitor:
but this resolution doesn't appear as an option in the settings drop-down, either within the Intel Control Panel:
...or in the Windows Control Panel:
When I view the monitor's properties under "Devices" in Windows and "List All Modes", Windows does not seem to know that the monitor is capable of 4K:
I tried setting a custom resolution of 4K for that monitor using the Intel Control Panel, which reluctantly seemed to work (it took a restart, I think), but I suffered a major RAM failure a few days later, which seemed to originate with the graphics card (the first sign of failure was the on-board screen flickering and becoming checkered before the computer became unresponsive). Because of that, I'm concerned that I could be damaging my hardware by setting a custom resolution through the Intel Control Panel, even if I'm setting a resolution that I know should work.
All my drivers are up-to-date, my HDMI 2.0 cable is able to support 4K, and I'm only using my on-board monitor or the external monitor, never both (so no cloning issues).
If this problem were always happening, then I'd try reinstalling Windows or flashing my BIOS, but the fact that it only happens some of the time makes me think that it's not the type of consistent problem that would come from issues at that level.
Does anyone have any clue how to fix this mess? I currently have a 4K monitor that I can't use, so I'd really appreciate your help. Thanks!
Lenovo ThinkPad T460s (type 20F9-CT01WW)
OS: Windows 7 Pro (x64)
CPU: Intel core i7-6600U @ 2.60 Ghz
Graphics: Intel HD Graphics 520 (capable of outputting 4K via HDMI, specifically 3840 x 2160 30p Hz)
(capable of displaying 3840 x 2160)